1.
Can you explain class and object with a Java
example?
Answer – Class and Object both are the basis of Object Oriented
Programming, and the concept of class and object revolves around the real-world
entities.
Class – A class in Java can be defined as a template or program
construct that is used to create objects, and also its methods and data types.
The declaration of a class may include various components such
as class name, body, modifiers, interface (not mandatory), and superclass (not
mandatory).
Let’s consider an example of class i.e. Student
Class Student
{
// instance variables declaration
// methods definition
}
Object – An object is known as the basic unit of Object Oriented
programming. It is a program construct that has state, behavior, and identity.
Many objects are created in a Java program that interacts by
invoking methods.
Let’s consider the object of the Student class, that will be a
specific student.
Student amaira = new Student ( );
It means one of the students of Student class is referred by ‘amaira’
2.
What are the basic concepts/principles of
OOPS?
Answer – The Object-Oriented Programming System is based on the
four basic principles, these are –
Abstraction – The abstraction is the concept of representing
essential features by hiding internal details or features.
Inheritance – The inheritance is the concept through which the
objects of one class are able to acquire the characteristics of the objects of
any other class.
Polymorphism – The polymorphism is the object-oriented
programming concept that enables the creation of a function, a variable or an
object with one name but in multiple forms.
Encapsulation – An another OOPS concept that is used to hide the
behaviour and properties of an object. This concept allows only appropriate
outside access. Also, it avoids other objects to access the properties and
methods of encapsulated object directly.
3.
Explain the basic features of Java.
Answer – Java was created with the aim of making a simple,
portable, and secure programming languages. Apart from these basic features,
Java has many other awesome features that make it so popular. These are –
·
Java is a simple programming language
·
Java is distributed
·
Java is faster i.e. high-performance
·
Java is dynamic in nature
·
Java is multithreaded
·
Java is robust in nature
·
Java is highly portable language
·
Java is independent of platform
·
Java provides high-level security
·
Java is architecture neutral
·
Java is an object-oriented programming language
4.
How is Java an object-oriented language?
Answer – Being an object-oriented programming language is an
important feature of Java. Let’s understand what makes it object-oriented.
·
Java follows Object Oriented programming model
·
Java is focused on the modular approach
·
Java follows the concept of abstraction
·
Java strictly follows object-oriented principle encapsulation
·
Java is based on the inheritance i.e. object-oriented concept
·
Java follows the object-oriented principle of polymorphism
5.
How will you compile a Java program?
Answer – In order to compile a Java program, follow the steps
mentioned below –
1.
Save the source code file with .java
extension. For example – student.java
2.
Javac compiler will then create a bytecode version of the source
file i.e. Student.class
3.
The bytecode is the executable code and thus executed by the
Java Virtual Machine (JVM), also known as Java runtime systems.
6.
What does “public static void main (String
args [ ] )“ signify? Explain.
Answer –
·
“public” is the access specifier
·
“static” is the access modifier that allows main ( ) method to
be invoked without creating any instance of the class
·
“void” is the return type that specifies that the main ( )
method won’t return any value
·
main ( ) is the pre-defined method that is called in the
beginning of a java program
·
“String args [ ]” are the arguments of the type String, when a
Java program is run, the Java application accepts it.
7.
What does “System.out.println ( )” specify?
Answer –
“System” is the pre-defined class in Java that gives access to the
system
“out” is the output stream
“println” is the method that is used to print line on
the console i.e. println is the console output statement
8.
What do you know about JVM?
Answer – The full form of JVM is the Java
Virtual Machine. Some important features of Java Virtual Machine are –
·
JVM is platform dependent
·
JVM is the runtime system of Java
·
JVM acts as an interpreter for the bytecode
·
JVM is responsible to maintain the security of the system
·
JVM is the what actually provides the environment for execution
- Define
garbage collection.
Answer – In Java, garbage collection is used to free up the
memory. It is done by clearing/deleting those objects which are no more
required by any program. Two steps are involved in the process of garbage
collection –
Step 1: Garbage Object Collection
This step involves the grouping and collection of all the
objects that are not referenced by any program. The garbage collector uses
various methods for the collection of garbage objects such as system.gc(
) or runtime.gc( )
Step 2: Run Finalize Method
After the collection of objects, the next step is to free the
memory space by deleting the objects that has been gathered by the garbage
collector. Then, Finalize method is executed in order to delete all the objects
that are dynamically created.
10. Define
polymorphism.
Answer – The meaning of word polymorphism is – one name and many
forms. Polymorphism refers to the characteristic of methods to act differently
on the basis of the calling object. Followings are the key features of
polymorphism –
·
It allows the use of one interface to implement various methods
·
It supports method overloading i.e. allows the use of multiple
methods with same name but different arguments.
·
It supports method overriding I.e. allows the use of multiple
methods with same name, same argument, and return type.
11. What do
you know about constructor?
Answer – A constructor can be defined as a block of code very
similar to the method that is called on the creation of an instant of the
object. The features of the constructor are as follows –
·
The name of the constructor is same as that of
the name of the class.
·
It doesn’t have any return type.
·
It is not considered as the class member like other methods.
·
It is invoked automatically when a new instance of an object is
created.
·
It can not be inherited like other methods of the class.
·
It is not compulsory to create a constructor for the class.
Advanced Java Interview Questions
In the second section, we cover the advanced Java interview
questions and answers for freshers as well as experienced professionals. If you
are looking for some advanced Java interview questions to crack the Java
interview and get a better job, these advanced Java interview questions for
experienced are only for you. If you have any other Java interview questions
for freshers or experienced professionals, please post in the comment section.
12. What
are the different Access Specifiers in Java?
Answer – Access Specifiers are used to setting the access level
of the classes and the methods, fields, and constructors in the classes. There
are four different types of Access Specifiers in Java –
·
Public – The classes,
fields, and methods defined by public access specifier, are accessible by every
class.
·
Private – The fields and
methods defined by private access specifier are accessible within the same
class to which those fields and methods belong. The private fields and methods
can’t even be inherited by any subclasses.
·
Protected – The fields and
methods defined by protected access specifier are accessible only in the class
to which those fields and methods belong.
·
Default – Default means no
specifier. When the methods, fields, and classes are not defined by any access
specifier, then those methods, fields, and classes are accessible in the
package to which those methods, fields, and classes belong.
13.. What are the different method signatures in Java?
Answer – A method inside a class is the sequence of statement to
perform a specific task.
Method Signatures: A number of parameters
such as method name, return type, access specifiers etc. constitute the method
signature. The various elements of the method signature are –
Method name – Method name is the mandatory
signature, such as display ( )
Return type – Return type of the method is also the
mandatory method signature, it can be void, int, float, string etc.
Access Modifier – It is the method
signature that is not compulsory to be defined. It can be synchronized, static,
etc.
Access Specifier – Not mandatory
method signature; access specifier can be private, public, protected etc.
Parameters – A method may either have or not
parameters; these are given in parenthesis such as (String name, int number);
A few examples of methods with the signatures are –
public static void getFinalName (String Name) { }
Void displaySum ( ) { }
public synchronized int getSalary (double grossSalary) { }
14. What is
a thread? What do you know about its lifecycle?
Answer – A thread is an execution in the program which follows
the single flow of control. The life cycle of thread comprises of the five
states, that are being mentioned below –
Newborn state – When an instance of
the thread is created, the thread is considered to be in this newborn state. In
this state, the thread is not considered alive, and the state exists before the
start ( ) method is invoked.
Runnable state – The life of the
thread starts from this state i.e. runnable state. When the start ( ) function
is invoked, the thread enters in the runnable state.
Running state – When the thread enters
the runnable state, it is ready to run and start the program execution. When
the thread is actually in the execution phase, it is said to be in the running
state.
Blocked state – During the running state,
the thread may have to wait for the resources that are being used by any
another thread. During the waiting phase, the thread is known to be in the
blocked state.
Dead state – When the execution of the program is done
and the run ( ) method is completed, the thread is said to be in the dead
state. After this state, a thread cannot be in execute or run again.
15.
What are the Applets?
Answer – Applets are the small Java programs that can be sent
from one computer to the other computer over the network with the use of Applet
Viewer that supports Java.
Applets have following properties –
·
Being a Java program, an applet can be run in
a web browser
·
It has the set of whole Java API
·
Applets are known to be the fully functional Java application
·
Applets offer a high-level security, called sandbox security
·
Applets follow the security ruled of the web browser
16. Mention
the situations when you will prefer to use interfaces and when abstract
classes.
Answer – It depends when a Java programmer will use interfaces
and when abstract class. Let’s discuss both one by one –
Abstract Classes are used –
·
When you need to make multiple implementations
of the same kind with common behaviour
·
In order to create inheritance hierarchies (already planned)
·
When you have to leave the implementation task on the inheriting
subclass by enabling the generalised form of abstraction
Interface is used –
·
When you need multiple classes to use some
methods that are not to be included in the class
·
When multiple implementations share the signatures of method or
program design is changed frequently
17. How are
the source code files named in Java?
Answer – The name of the Java source code file is same as that of
the public class or interface, defined by programmer during writing the program
code. It is restricted that source code won’t contain more than one public
class or interface. While naming a Java source code file, there may be
occurrence of two different cases –
Case 1: When there is no public class or interface in the source code
file –
Although it is mandatory that source code file will contain only
one public class or interface but it may not contain any public class or
interface. In this case, the java source code file will be named something else
except its interfaces and classes.
Case 2: When there is one public class or interface in the source code
file –
It is the case when one public class or inheritance occur in the
source code file. In this case, the name of the java source code file will be
same as that of the public class or interface that has been defined in the
program code.
18.
What do you mean by the nested class?
Answer – In general, the meaning of nested means one in another.
In Java, a nested class means a class within another class i.e. the class that
is declared inside an another class is the nested class.
Some times, the nested class is also known as the inner class.
The Syntax is –
class Parent_class
{
//code
class Nested_class
{
//code
}
}
Advantages of nested class in Java
·
Permitted to access all the methods and data
members (including private) of the outer class
·
As it groups interfaces and classes in one place, thus develops
easily maintainable and readable code
·
Less code is required to be written
19. Does
Java support networking?
Answer – Yes, Java supports networking. There are two types of
classes in Java to support networking i.e. low-level and high-level. These
classes control the network applications programming. As Java is platform
independent in nature, Java networking is also platform independent.
The classes to support Java networking are –
·
Low-level classes – These
classes support socket programming like DataramSocket, Socket, and ServerSocket
classes.
·
High-level classes – These
classes provide support for URLEncoder, web programming URL, and URL
connection.
20. Is
there any alternative to inheritance? Explain.
Answer – Yes, there is an alternative to inheritance in Java;
Delegation. Followings are the important points about delegation –
·
Delegation specifies that there exists an instance of any class
that works as the instance variable and used to send messages to that instance
of the class.
·
Delegation is comparatively safer than that of the inheritance
as the programmer doesn’t need to think about the forwarded message. As the
instance belongs to the existing known class and doesn’t make you accept all
the methods of superclass, only the selected and required methods can be
provided.
·
Due to delegation, the programmer have to write more code. Also,
it is harder to reuse the delegation unlike inheritance as it is not a
subclass.
- What
is the difference between JDK, JVM, and JRE?
Answer – The difference between JDK, JVM, and JRE is as follows:
JDK – JDK stands for Java Development Kit. JDK is
the most commonly used software development environment for Java programmers.
It is meant for the development of Java applications and applets. It consists
of Java Runtime Environment, a compiler (javac), an interpreter (Java), an
archiver (jar), a generator for documentation (Javadoc), and some other tools
that are required in the development of Java applications.
JVM – JVM is an acronym for JavaVirtual Machine. It
acts as an interpreter for the byte code. It is the real runtime system of Java
and provides an environment for the execution of Java programs and
applications. Most important, Java Virtual Machine is independent of the
platform.
JRE – JRE is the Java Runtime Environment, also
known as Java RTE. It is the Java Virtual Machine implementation that is
responsible for the execution of Java applications. It provides everything that
is required for the execution of a Java application. It comprises of the Java
Virtual Machine, supporting files, and core classes.
22. What is
the difference between WAR and JAR files?
Answer – The difference between WAR and JAR files is being
described in the following table –
|
WAR Files
|
JAR Files
|
|
1. The term WAR files stand for the Web Archive Files.
|
1. The term JAR files stand for the Java Archive Files.
|
|
2. WAR files are responsible for the storage of Java classes,
XML, and JavaServer pages.
|
2. Java files allow the aggregation and storage of multiple
Java files into a single file.
|
|
3. WAR files are mainly used for the purpose of web
applications.
|
3. JAR files are mainly used to handle Java classes in a
library.
|
23.
What exactly happens when an object is created
in Java?
Answer – When an object is created in Java, a number of things
happen in a specific sequence to ensure whether the object has been created
properly, these are –
1.
Memory Allocation –
The memory is allocated for the storage of all the instance variables and the
other data of object and its superclasses that are related to implementation.
2.
Initialization –
After memory allocation, the objects are declared and initialized with their
default values.
3.
Constructor – Next, the
constructors call other constructors for its superclasses. java.lang.Object is
the base class for all the objects in Java, so this process is repeated
continuously until the constructor for java.lang.Object is called.
4.
Execution – In this step, the
initialization of all the instance variable takes place and the initialisation
blocks are executed. After that the execution of the body of the constructor
takes place.
JDBC Java Interview Questions
In the third section, here we cover the JDBC Java interview
questions and answers. Go through these basic and advanced JDBC Java interview
questions and broaden your knowledge to crack the interview. If you have any
other JDBC Java interview questions, please post in the comment section.
24.
What do you know about JDBC?
JDBC is a Java API that is responsible for the connection and
execution of Java query with the database. JDBC API uses JDBC drivers to create
a connection between database and the query. JDBC API can be used to access
data from any relational database.
25.
What are the steps to connect a Java
application with the database using JDBC?
Answer – Followings are the steps that will connect a
Java application with the database using JDBC:
Step 1: Registration of the
driver class using forName( ) method of the Class class.
Step 2: Creation of connection
object using getConnection( ) method of the DriverManager class.
Step 3: Creation of statement
object using createStatement( ) method. Of the connection interface.
Step 4: Execution of the query
using executeQuery( ) method of the Statement interface.
Step 5: Closure of the connection
object using close( ) method of the Connection interface.
26.
Name different types of JDBC statements in
Java.
Answer – Following are the 3 different types of JDBC statements
in Java:
1.
Statement
2.
CallableStatement
3.
PreparedStatement
27. How
will you store an image in database?
Answer – In Java, the images can
be stored in a database with the setBinaryStream( ) methodof the
Prepared Statement interface. This method will set the Binary information into
the parameterIndex.
The syntax is –
Public void setBinaryStream(Int paramIndex,InputStream stream)
Throws SQLException
28.
How are the stored functions and procedures
executed in Java?
Answer – In Java, the stored
functions and procedures are executed with the help of CallableStatement
interface.
29.
Name the various components of JDBC API.
There are various components of JDBC API are classes and
interfaces that are stored in java.sql package, these are –
Classes – Blob, DriveManager, Types, Clob,
SQLException etc.
Interfaces – Statement, Connection, ResultSet,
PreparedStatement, DatabaseMetaData, ResultSetMetaData, CallableStatement etc.
30. What is
the batch processing technique in JDBC?
Answer – In Java, the batch
processing technique is used to perform the execution of multiple queries at
the same time. During batch processing, the grouping of related SQL statements
is done into a batch and then performs their execution instead of performing the
execution of a single query. In this way, the batch processing results in
faster execution of queries and improved performance.
31.
What do you know about Connection interface in
JDBC API?
Answer – The Connection interface
is used for the maintenance of a session with the database. It can also be used
for the management of transactions. It contains various factory methods that
returns the instance of CallableStatement, Statement, PreparedStatement, and
DatabaseMetaData.
32.
Differentiate statements execute, executeQuery,
and executeUpdate.
Answer – The difference between
execute, executeQuery, and executeUpdate is as follows –
execute (String query) – The execute
statement is used to perform the execution of SQL query. When the result is an
ResultSet, it returns TRUE, e.g. returns TRUE value for Update or Insert
queries.
getResultSet( ) method is used to get the ResultSet and
getUpdateCount( ) is method is used to get the value of update count.
executeQuery(String query) – The executeQuery
statement is used for the execution of Select queries and to return the
ResultSet. The value of ResultSet is never set to null even when no matching
record is found for the query.
executeQuery method should be used for the execution of Select
queries as it cannot be used for insert and update queries. It throws
java.sql.SQLException if someone executes update/insert query with the message
that executeQuery method cannot be used for update/insert.
executeUpdate (String query) – The execute
update statement is used for the execution of DML (i.e. Insert, Update, and
Delete) statements and also for DDL statements those don’t return any value.
For DML statements the return value is int and equals to the DML
statements row count. While in case of DDL statements, the return value is 0.
So, the execute( ) method is used only if you don’t know the
type of query statement else the use of executeQuery( ) and executeUpdate( )
methods is preferred.
33.
Name the interface that performs transaction
management in JDBC.
Answer – The Connection interface
performs the transaction management in JDBC. It provides various methods such
as rollback( ), commit( ) etc. that helps in transaction management in JDBC.
String Handling Java Interview Questions
The fourth section covers the String handling Java interview
questions and answers. Preparing through these String Java interview questions
will be highly helpful to crack the Java interview. If you have any other
String-based Java interview questions, please post in the comment section, we’ll
cover them up.
34.
Why are the string objects immutable in Java?
Answer – In general, the meaning of term
immutable is unchangeable i.e. that cannot be changed.
String objects are immutable in Java which means once the string
objects are created, it is not possible to change its value.
String objects are immutable as Java is based on the concept of
string literal. To understand this, consider that 5 references are there, all
of which refers to the one object called “naira”. In this case, if the value of
the object is changed by one reference variable, it will also affect the value
of the other reference variables. This is the reason why string objects are
immutable in Java.
35.
What are the different ways to create String
objects in Java?
Answer – There are two ways to create String
objects in Java:
·
By String Literal
String object using String literal is created by using double
quotes. For example –
String s=“hello”;
Every time, when you create a string literal, JVM checks string
constant pool to find if the string already exists. If the string already
exists, it will return a reference to the pooled instance. If the string is not
already there in the pool, JVM creates the new string and store it in the pool.
Now consider,
String s1=“hey”;
String s2=“hey”;
Here, the second statement will not create the new instance as
the first statement has already created that.
·
By New Keyword
This is an another method to create String objects in Java using
new keyword. For example –
String s=new String(“Niharika”);
This statement will create two objects and one reference
variable.
In this case, JVM creates a new string object in a heap memory
and the literal “Niharika” will be stored in the constant pool of the string.
The variable s refers to the String object in the heap.
36. Differentiate
StringBuilder and StringBuffer in Java.
Answer – The basic difference
between StringBuilder and StringBuffer is given as –
StringBuffer – It is a user mutable string i.e. its
value can be changed any time after it has been created. The objects that are
created using StringBuffer, are stored in the heap and StringBuffer is thread
safe.
StringBuilder – It is also a user
mutable string i.e. its value can be changed any time after it has been
created. StringBuilder also stores the objects in heap like StringBuffer but
the main difference is that StringBuilder is not thread safe.
|
Index
|
StringBuffer
|
StringBuilder
|
|
Modifiable
|
Yes, it can be modified or changed i.e. mutable
|
No, it can’t be modified or changed i.e. immutable
|
|
Storage Area
|
Objects created through StringBuffer are stored in heap.
|
The objects created through StringBuilder are stored in heap.
|
|
Thread Safe
|
Yes, it is thread safe.
|
No, it is not thread safe.
|
|
Synchronization
|
All the methods in StringBuffer are synchronized
|
Methods are not synchronized in StringBuilder
|
|
Method Access
|
A method can access only one thread at a time
|
A method can access multiple threads simultaneously at a time
|
|
Performance
|
StringBuffer is slower than StringBuilder even while calling
the same methods of a class
|
StringBuilder is faster when it comes to calling the same
methods of a class
|
|
Conversion
|
StringBuffer to String conversion can be done by using
toString ( ) method, + “” or String.valueOf ( ) method
|
StringBuilder to String conversion can be done by using
toString ( ) method.
|
37. How
will you create an immutable class in Java?
Answer – There are a number of immutable classes
in Java such as Boolean, Integer, Float, Long, Double, Short, Byte, String etc.
To sum up, String class and all the wrapper classes are immutable. An immutable
class can also be created by creating a final class containing final data
members.
A class is said to be final when
·
The class itself is final i.e. it is not possible to create its
subclasses.
·
It has a final instance variable i.e. it is not possible to
change its value after the creation of an object.
·
There are no setter methods i.e. there will not be any option to
change the value of instance variable.
For example –
public final class Student
{
Final String idNumber;
public Employee(String idNumber)
{
this.idNumber = idNumber;
}
public String getidNumber( )
{
return idNumber;
}
}
This is a final class with name Student that contains one
parameterised constructor, one final data member, and a getter method.
38. Why
does the Java use the concept of string literal?
Answer – Java uses the concept of string literal
as it makes Java more memory efficient. It is because the concept of string
literal doesn’t create a new String object if that is already existing in the
String constant pool. It avoids the redundant storage and thus saves memory.
39. How
many String objects the following code will create? Explain.
·
String s1 = “Hello”;
·
String s2 = “Hello”;
·
String s3 = “Hello”;
·
String s4 = “Hello”;
·
String s5 = “Hello”;
Answer – The given code will create only one
String object.
Explanation – Only the first statement will create
the String object “Hello”. For the next statements, as the string is already
there in the constant pool, JVM will not create any instance instead will
return a reference to the pooled instance.
40. What is
the main difference between string and stringbuffer object?
Answer – The main difference between string and
stringbuffer object can be explained in terms of the mutability.
String object is immutable while StringBuffer object is mutable.
41.
What is the use of toString() method in Java?
Answer – The toString() method returns the object
representation. Whenever an object is printed, Java complier will invoke the
toString() method for that object. This overriding of toString() method will
return the desired output on the basis of your implementation.
Exception Handling Java Interview
Questions
The fifth section covers the Exception handling Java interview
questions and answers. Preparing through these Exception Handling Java
interview questions will be highly helpful to crack the Java interview.
If you have any other Exception-based Java interview questions, please post in
the comment section, we’ll cover them up.
42.
What is exception handling?
Answer – Exception handling can be defined as the process of
handling runtime errors such as IO, Remote, ClassNotFound, Remote etc.
The exceptions may effect the normal execution of application,
that’s why the exception handling is used.
Importance of exception handling
Exception handling is very important while creating Java
programs and applications. It is important as it helps to maintain the normal
flow of the application avoiding any disruption (i.e. runtime error).
43.
What is an exception? How is it different from
error?
Answer –
In general terms, exception is something that creates abnormal
condition.
In Java, the runtime errors are known as exceptions. These are
the events or conditions, thrown at the runtime and affects the normal flow of
a program.
Difference between Exception and Error –
The exceptions are the recoverable conditions that thrown at
runtime while errors are the irrecoverable conditions that are also thrown at
runtime.
The example of exception is FilenotFoundException that will be
thrown when the particular file is not found or that does not exist.
The example of error is OutofMemory.
44.
Name the keywords that are used to handle
exceptions in Java.
Answer – The Java exceptions are handled by the
use of five keywords:
throw
throws
finally
try
catch
45.
Differentiate checked exception and unchecked
exception.
Answer – The differences between checked exception and unchecked
exception are as follows:
|
Checked Exception
|
Unchecked Exception
|
|
The checked exceptions are those which are checked at the
compile time.
|
The unchecked exceptions are those which are not checked at
the compile time.
|
|
These exceptions are thrown by the classes that extend
Throwable class except RuntimeException.
|
These exceptions are thrown by the classes that extend
RuntimeException.
|
|
The examples are SQLException, IOException etc.
|
The examples are NullPointerException, Arithmetic Exception
etc.
|
46.
Explain the hierarchy of exception in Java.
Answer – The hierarchy of exception in Java can
be explained by the following –
The parent class of all the Exception and Error classes is the
Throwable class. The exceptions are classified into two types – Checked
Exceptions and Unchecked Exceptions. Also, the errors are of two types –
Assertion Errors and Virtual Machine Errors.
47. Explain
some of the methods of Exception class in Java.
Answer – The specific methods used to handle
exception handling are not present in the Exception class andlasses but all the
exception handler methods are defined in the parent class i.e. Throwable. Some
of the methods that are used for exception handling are:
String toString( ) – The information
about Throwable is returned by this method in String format. The output String
of this method contains a localized message along with the name of the
Throwable class.
String getMessage( ) – The result of this
method is the message String of Throwable.
Synchronized Throwable getCause( )- The output of this method
specifies the cause null id or the exception.
String getLocalizedMessage( ) – This
method is overriden by the subclasses to provide specific localized message to
the calling program. In Throwable class, this method is implemented just by
using getMessage( ) method which returns the exception message.
void printStackTrace( ) – This method
is used to print the information about stack trace. This is an overloaded
method. In order to write stack trace information to the stream or file, we can
pass PrintWriter or PrintStream as argument of this method.
48. Write
some statements the will create custom Exceptions.
Answer – The custom exceptions can be created by extending the
Exception class or its subclasses.
Example 1:
class NewException extends ArithmeticException{
}
//this will create Unchecked Exception
Example 2:
class NewException extends Exception
{
}
//this will create Checked Exception
Example 3:
Class NewException extends IOException
{
}
//this will create Checked Exception
49.
Is it possible to use try block without catch
block?
Answer – Yes, it is possible to use try block without catch
block. It is not always required that the try block should be followed by a
catch block. Try block can also be followed by a finally block. And the
exceptions that are to be thrown should be declared in the throws clause of the
method.
50.
In which case the finally block will not be
executed?
Answer – In case of the program exit, the finally block will not
be executed. So, when the program exits either by causing a serious error that
may cause the abortion of the process or by calling System.exit() method, it
will stop the finally block from execution.
51.
Differentiate throw and throws.
Answer – The main differences between throw and
throws are as follows –
|
Throw
|
Throws
|
|
1. Throw is used to trigger the expectation.
|
1. Throws is used for the declaration of an expectation.
|
|
2. Throw is used inside the method body
|
2. Throws is used in the method signature.
|
|
3. Throw is followed by the instance of exception class, such
as
Throw
new ArithmeticException (“Arithmetic Exception”);
|
3. Throws is followed by the name of exception class, such as
Throws
ArithmeticException;
|
|
4. Using throw, one exception can be handled at a time.
|
4. Using throws, multiple exceptions can be declared at the
same time.
|
52.
How will you differentiate final, finalize,
and finally?
Answer – The difference between final, finalize, and finally is
as follows –
Final – In Java, Final is a keyword that is used
to define constants.
Once a class is declared as final, it can not be divided into
subclasses.
Once a field is marked as final, its value becomes constant that
cannot be reset.
When a method is declared as final, subclasses cannot override
that method.
Finalize ( ) – Finalize method in
Java is associated with the garbage collection.
The finalize method is automatically invoked before the garbage
value collection.
Finally – Finally block in Java is used with the
try and catch blocks (except when try block uses System.exit(0) call)
The finally block is meant for the unexpected error. It executes
the last clause mentioned in the try catch block.
The finally block contains a set of statements thats execution
does not depend on the exception caught by the previous catch block.
Servlet Java Interview Questions
Here in sixth section, we cover the list of Servlet Java
interview questions for the freshers and as well as professionals. If there is
any Servlet-based Java interview question, you want to find the answer, post it
in the comment section and our expert team will respond with the detailed
answer.
53.
What do you know about Servlet?
Answer – Servlet in Java is server side technology that provides
support for the data persistence and dynamic response and thus enhance the web
servers capabilities. Some important points about Java Servlets are –
·
There are two types of packages i.e. javax.servlet and
java.servlet.http that provides classes and interfaces to write own servlets.
·
javax.servlet.Servlet interface is responsible to define the
methods for servlet lifecycle, so it is mandatory for all the servlets to
implement java.servlet.Servlet interface.
·
Java Servlet API provides GenericServlet class that can be
extended during the implementation of any generic service.
·
The HttpServlet class contains methods to handle HTTP specific
services i.e. doPost( ) and doGet( ).
·
As the http protocols are mainly used to access the web
applications, HttpServlet class is extended.
54. What
are the different stages in a servlet lifecycle?
Answer – The lifecycle of a servlet comprises of the 5 stages:
Loading – The servlet class is loaded
Instant Creation – The servlet instance is created
Initialization – Init method is invoked and the servlet becomes
ready
Service Request – Service method is invoked to perform any task
Destruction – invocation of destroy method and the destruction
of servlet
55. Explain
the working of cookies in Servlets.
Answer – Cookies are the text that are sent to the client by
server, and is saved at client side. Servlet APIs contain
javax.servlet.http.Cookie class which implements Cloneable and Serializable
interfaces an thus provides cookies support.
HttpServletRequest getCookies( ) method is used to get the array
of cookies from the request.
HttpServletResponse addCookie (Cookie c) method is used to
attach the cookie in response header.
As there is no need to add cookie to the request, no method is
there to add or set cookie to the request. Similarly, there is no getter method
for the cookies in servlet.
56.
What are the various methods to manage session
in Servlets?
Answer – Session is a state of conversation between the server
and the client. It may consist of a number of requests and responses between
the server and the client. Session is maintained through session id (that is
the unique info about the session). The session id is passed between client and
server during every request and response.
There are different methods for the management of sessions in
servlets –
Cookies
URL Rewriting
HTML Hidden Field
User Authentication
Session Management API
57.
Differentiate between Get and Post methods.
Answer – The difference between Get and Post methods is as
follows –
|
Get Method
|
Post Method
|
|
Get method is used to request data from a particular resource
i.e. server
|
Post method is used to return the requested data to a
particular resource i.e. client
|
|
The request data is sent in the header, so only the limited
data can be sent
|
The response data is sent in the body, so large amount of data
can be sent
|
|
doGet method of servlet handles the Get method
|
doPost method of servlet handles the Post method
|
|
Get method is no secure as the data is visible in the URL
|
Post method is secured as the data is not visible in the URL
|
|
It is possible to bookmark Get method
|
It is not possible to bookmark Get method
|
|
Get method is idempotent i.e. it provides same result on the
multiple executions
|
Post method is non-idempotent i.e. it provides different
results on the multiple executions
|
|
The Get method is most commonly used and is more efficient as
compared to the Post method
|
The Post method is less used and is even less efficient as
compared to the Get method
|
58.
Differentiate ServletConfig and
ServletContext.
Answer – In servlet, the
difference between ServletConfig and ServletContext is as follows –
|
ServletConfig
|
ServletContext
|
|
It denotes single servlet
|
It denotes the complete set of running web application, and is
same for all the servlets
|
|
The scope of ServletConfig is servlet wide as it is defined
within the servlet section of the web.xml file
|
The scope of ServletContext is application wide as it is
define outside the servlet section of the web.xml file
|
|
getServletConfig( ) method provides the config object
|
getServletContext( ) provides the context object
|
|
It belongs to a specific servlet so acts as a local parameter
|
It belongs to the whole web application so acts as a global
parameter
|
59.
What do you understand by servlet
collaboration?
Answer – The communication between
two servlets is known as the servlet collaboration. The different methods
through which servlets communicate like sendRedirect( ) method,
RequestDispacher interface and others.
60.
How will you differentiate sendRedirect( )
method and forward( ) method?
Answer – The difference between
sendRedirect( ) and forward( ) method is as follows –
|
sendRedirect( ) method
|
forward( ) method
|
|
sendRedirect( ) method uses browser URL bar so, always
sends a new request
|
forward( ) method sends the existing request from a servlet to
the resource of another servlet
|
|
The scope of sendRedirect( ) method is not only within the
server but also outside of the server
|
The scope of forward( ) method id within the server I.e. it
can’t work outside the server
|
|
sendRedirect( ) method works at the client side
|
forward( ) method works at the server side
|
61.
What is the meaning of session tracking?
Answer – Session indicates a
specific time interval in servlet while session tracking is a method to manage
or maintain the user state, also known as session management in servlet.
As the http protocol is stateless due to which every request
generated by a user is consider it is required to maintain the state using any
of the session tracking techniques. The session tracking is done to recognize a
particular user.
62.
Explain cookies in servlet.
Answer – Cookie is defined as a
small piece of information that continues to remain between the requests of
multiple clients.
Cookie has a name, value, and some other attributes version
number, domains and path qualifiers, comment, and a maximum age.
A cookie can be persistent, that remains valid for multiple
sessions or non-persistent that remains valid only for one session.
Hibernate Java Interview Questions
Here in seventh section, we’ll cover the list of Hibernate Java
interview questions. If there are any Hibernate Java interview questions, you
want to find the answer, just post it in the comment section and our expert
team will respond with the detailed answer.
63.
What do you know about hibernate framework?
Answer – Hibernate is a lightweight, open source, ORM tool. The
hibernate framework is meant to simplify the Java application development in
order to interact with the database.
The hibernate framework has many advantages, these are:
·
Hibernate framework is lightweight and open source under LGPL
licence.
·
Hibernate framework uses Hibernate Query Language (HQL) that is
independent of database.
·
Due to the use of cache, the performance of hibernate framework
is very fast.
·
It make complex joins simpler so it is easy to retrieve data
from multiple tables.
·
Hibernate framework facilitates the automatic creation of tables
of the database.
·
With the Query cache supporting feature, hibernate framework
provides status of database and statistics of query.
64. Define
ORM.
Answer – Object Relation Mapping (ORM) is a technique of
programming used for the mapping of data with the data stored in the database.
An ORM tools makes the process of data access, data creation, and data
manipulation simpler.
The Object Relation Mapping tool uses JDBC APIs to create an
interaction with the database.
65.
What do you know about Hibernate Query
Language (HQL)?
Answer – Hibernate Query Language is an object oriented query
language that is much similar to the Structured Query Language.
Hibernate Query Language (HQL) has some advantages over
Structured Query Language (SQL), these are –
·
HQL is independent of database; no need to change the HQL query
if database is changed
·
The previous knowledge or experience with SQL is not required to
work with HQL
·
It is easier and simpler to write query with HQL as compared to
SQL
66.
Name the core interfaces of Hibernate.
Answer – There are six core interfaces in the hibernate
framework, these are:
·
Session
·
SessionFactory
·
Configuration
·
Criteria
·
Query
·
Transaction
67. Differentiate
first level cache from second level cache.
Answer – The first level cache is different form second level
cache in hibernate. The differences between the two are:
|
First Level Cache
|
Second Level Cache
|
|
The first level cache is associated with the Session interface
of hibernate.
|
The second level cache is associated with the SessionFactory
interface of hibernate.
|
|
The first level cache is by default enabled.
|
The second level cache is not by default enabled. It is
required to enable it manually.
|
68.
How many states of object are there in
hibernate?
Answer – There are 3 states of object in hibernate:
1.
Transient – When the object is
created, it is said to be in the transient state. In the transient state, the
object does not have any primary key. Also, the session is not created for the
object in this state.
2.
Persistent – When the session is
created for the object and is open, the object is said to be in persistent
state. This state starts when the instance of the object is saved in the
database or retrieved from the database.
3.
Detached – When
the session of the object is closed, the object is said to be in detached state.
The object can also reach to the persistent state again after this state if you
invoke update() or lock() method.
69. Name
the different types of association mapping in hibernate.
Answer – There are four different types of association mapping in
hibernate.
·
One to One
·
Many to One
·
One to Many
·
Many to Many
70. Differentiate
persist() and save() method of session of the hibernate.
Answer – Following is the difference between persist() and save()
method of session of the hibernate.
|
persist( )
|
save( )
|
|
The persist( ) method does not return anything.
|
The save( ) method returns the instance identifier.
|
|
The syntax of persist( ) method is –
public
void persist(Object a)
|
The syntax of save( ) method is –
public
Serializable save(Object a)
|
|
It’s return type if void.
|
It’s return type is Serializable.
|
71.
Name the different strategies for inheritance
mapping in hibernate.
Answer – There are three different types of strategies for
inheritance mapping in hibernate:
·
Table per subclass; the tables are created according to the
class but related to the foreign key
·
Table per hierarchy; only one table is created to map the whole
hierarchy
·
Table per concrete class; tables are created according to the
class.
72. How
will you make a class immutable in hibernate?
Answer – By default, a class is set to be mutable with the true
value of mutable i.e. mutable = “true”. In order to make a class immutable, you
will require to mark the value of mutable false i.e. mutable = “false”.
73. Differentiate
merge() and update() method.
Answer – The difference between merge() and update() method is as
follows:
|
merge() method
|
update() method
|
|
The merge method is used to combine something.
|
The update method is used to edit something.
|
|
The merge method is used when the state of the session is not
known.
|
The update method is used when the session is not in the
persistent state.
|
|
It is used to make the modifications at any time.
|
It is only used inside the session.
|
|
It doesn’t throw an error when session is in detached state.
|
It throws an error when session is in detached state.
|
74.
What do you know about lazy loading in
hibernate?
Answer – Lazy loading is a technique that is used to improve the
performance in hibernate. It results in faster performance by loading the child
object on the basis of demand.
Lazy loading is by default enabled in Hibernate 3 and later
versions. It means you don’t require to set the value of lazy to true I.e. lazy
= “true”. It specifies that you won’t require to load child objects if the
parent object has already been loaded.
Spring Java Interview Questions
In the eighth section, here we cover the Spring Java interview
questions and answers. Go through these basic and advanced Spring framework
Java interview questions and broaden your knowledge to crack the interview. If
you have any other Spring-based Java interview questions, please post in the
comment section.
75.
Define Spring and explain the advantages of
spring framework.
Answer – Spring is a lightweight, integrated, and loosely coupled
framework that is used for the development of the enterprise applications with
Java programming.
Sometimes the Spring framework is considered to be the framework
of frameworks as it supports many frameworks such as Hibernate, Struts, EJB,
Tapestry, JSF etc. Followings are the advantages of spring framework –
·
Lightweight
·
Integrated
·
Loose Coupling
·
Predefined Templates
·
Easy Testing
·
Faster Development
·
Declarative Support
·
Powerful Abstraction
76. What
are the various Spring Modules?
Answer – The spring framework is consisted of various modules
which are grouped as Test, Spring Core Container, Instrumentation, Aspects,
AOP, Web (MVC/Remoting), and Data Access/Integration.
Let’s know more about these modules of spring framework –
Test – The test layer is responsible to provide the
testing support with the testNG and JUnit modules.
Core Container – The spring core
container is composed of three modules, these are –
Context – It supports EJB, Internationalization,
Basic Remoting, and JMS.
Core and Beans – It provides
Dependency Injection and IOC features.
Expression Language – It provides support to
accessing indexers and collections, getting and setting property values,
arithmetic and logical operators, method invocation, named variables, object
retrieval by name and others.
Instrumentation, Aspects, and AOP – The
instrumentation module is meant to support to the class loader and class
instrumentation implementations.
The aspects module is made to support the integration by means
of the AspectJ.
The AOP module is known to provide support to the implementation
of the aspect-oriented programming to make use of pointcuts, advices etc. for
the decoupling of the code.
Web (MVC/Remoting) – This layer of spring
framework is composed of Web, Web-Struts, Web-Servlet, and Web-Portlet modules
which are used to provide support for the development of web applications in
Java.
Data Access/ Integration – This
group in spring framework includes OXM, JDBC, JMS, ORM, and Transaction modules
which are made to provide support for the database interaction.
77.
Explain Autowiring in Spring.
Answer – Autowiring is a programming technique that helps
programmer to automatically inject the bean without writing any injection logic
explicitly.
The code for the bean injection (with the help of dependency
injection) is –
<bean id= “emp” class= “com.javapoint.Student” autowire=
byFName” />
There are different autowiring modes in spring, these are –
|
Name of Autowiring Module
|
Details
|
|
constructor
|
It performs the injection of bean using constructor.
|
|
byName
|
It performs the injection of bean on the basis of the name of
the property by using setter method.
|
|
byType
|
It performs the injection of the bean on the basis of the type
of the property by using setter method.
|
|
no
|
This mode specifies that the autowiring is disable. It is the
default mode of the autowiring.
|
78.
Explain various bean scopes in Spring.
Answer – The spring framework contains 5 bean scopes that are
explained below:
|
Name of the Scope
|
Description
|
|
session
|
The instance of the bean is created as per the HTTP session.
|
|
request
|
The instance of the bean is created as per the HTTP request.
|
|
prototype
|
The instance of the bean is created at the time when it is
requested.
|
|
globalsession
|
The instance of the bean is created as per the global session
of HTTP.
|
|
singleton
|
The instance of the bean is created only once and is returned
by the IOC container. Singleton is the default spring scope.
|
79.
Mention some Spring annotations you have used.
Answer – Here are the spring annotations that I’ve used in my
Java projects:
@ResponseBody – to send Object as
response. It was mainly used for sending JSON and XML data as response.
@Controller – used for controller
classes
@PathVariable – to map dynamic values
from URI to handler method arguments
@RequestMapping – to configure URI
mapping in controller handler methods
@Qualifier – for avoiding confusion among multiple
instances of bean type
@Autowired – to autowire dependencies in beans
@ Scope – for the configuration of
the scope of bean in spring
@Service – used for service classes
@ComponentScan, @Configuration, and @Bean – used
for the configurations based on Java
@Aspect, @After, @Before, PointCut, and @Around – for
the configuration of advices and aspects
80.
Have you ever integrated Spring framework with
Hibernate framework? Explain.
Answer – Yes, I have integrated Spring framework with Hibernate
framework by using Spring ORM module.
While using Hibernate 3+ where current session is provided by
SessionFactory, HibernateDaoSupport and usingHibernateTemplate classes should
be avoided. Instead, DAO pattern was used along with dependency injection for
the purpose of integration.
Spring ORM was used over Hibernate boiler-plate code in order to
implement transaction management
81.
What do you know about IOC? Explain in detail.
Answer – IOC is an abbreviation for Inversion of Control, it is a
design pattern that is used to provide loose coupling. it is a container that
is responsible for instantiation, configuration, and assembly of the objects.
It retrieves information from XML files and then works. It is used for the
removal of the dependencies from the program.
IOC container is responsible to perform the following functions
–
For the instantiation of the application class
For the configuration of the object
In order to assemble the object’s dependencies
Sample IOC Code:
public class Student{
Name name;
Student(Name name){
This.address=address;
}
}
82.
Explain how is exception handling performed in
Spring framework.
Answer – There are different ways to handle exceptions in spring
framework:
Global Exception Handler – The exceptions can
be handled by defining global exception handler. The global exception handler
can be defined by using @ControllerAdvice annotation with the class.
Controller based – In this, the exception
handler method is defined in the controller classes. The annotation
@ExceptionHandler is used for controller based exception handling.
Implementation of HandlerExceptionResolver – In
static pages, it is required to handle the generic exceptions. For this, the
HandlerExceptionResolver interface in Spring framework is implemented for
creating global exception handler.
83.
State the advantages of JdbcTemplate in
Spring.
Answer – Followings are the advantages of JdbcTemplate in Spring:
·
JdbcTemplate provides various methods using those you can
directly write the queries. In this way, JdbcTemplate saves the a lot of time
as well as work.
·
When you use JdbcTemplate class, you don’t require to create
statement, connection, close connection, start transaction, and commit
transaction for the execution of various queries. So, JdbcTemplate class allows
the programmer to perform direct execution of the query.
84. Name
the different types of advice in Spring Aspect Orient Programming (AOP).
Answer – The Spring AOP provides of five types of advices, these
are –
·
Around Advice
·
Throws Advice
·
After Advice
·
After Returning Advice
·
Before Advice
85. Differentiate
between ApplicationContext and BeanFactory.
Answer – The difference between ApplicationContext and
beanFactory is as follows:
|
ApplicationContext
|
BeanFactory
|
|
The ApplicationContext is an advanced spring container.
|
The BeanFactory is a basic spring container.
|
|
The ApplicationContext is the extension of the BeanFactory
interface.
|
The BeanFactory interface is not an extended interface.
|
|
ApplicationContext interface provides some additional
facilities – message resource handling, integration with spring AOP, and many
others.
|
BeanFactory interface provides the basic facilities.
|
JSP Java Interview Questions
In this ninth section, we cover the JSP Java interview questions
and answers. Go through these JSP Java interview questions and prepare yourself
for the Java interview. If you have any other JSP Java interview questions,
please post in the comment section.
86.
What is JSP?
Answer – Java Server Pages (JSP) is a Java technology that is
used to develop web applications. It offers some more functionality and
features than servlet i.e. JSTL, expression language, custom tags etc. so it is
considered as the extension of servlet technology.
A Java Server Page is composed of JSP tags along with HTML tags.
It is easy to maintain JSP pages as it does not combine development and
designing.
Advantages of JSP –
·
Easy to maintain
·
Additional functionality
·
Faster development
·
Less coding
87. Explain
the lifecycle of a JSP page.
Answer – The lifecycle of a JSP page involves following phases –
JSP Page Translation
JSP Page Compilation
Class file loading by class loader (Classloading)
Creation of generated servlet object (Instantiation)
Invocation of jspInit( ) method by container (Initialization)
Invocation of jspService( ) method by container (Request
Processing)
Invocation of jspDestroy( ) method by container (Destroy)
88.
What do you know about JSP Implicit Objects?
Answer – JSP Implicit Objects are those which are created by the
web container and can be used by any of the JSP page. In Java, nine JSP
Implicit Objects are there.
Following table covers all the JSP implicit object with their
types.
|
Object Name
|
Object Type
|
|
Request
|
HttpServletRequest
|
|
Page
|
Object
|
|
pageContext
|
PageContext
|
|
Application
|
ServletContext
|
|
Session
|
HttpSession
|
|
Out
|
JspWriter
|
|
Config
|
ServletConfig
|
|
Exception
|
Throwable
|
|
Response
|
HttpServletResponse
|
89.
What do you know about JSTL?
Answer – JSTL stands for JSP Standard Tag Library that contains a
set of tags for the development of JSP pages.
·
JSTL has the following advantages –
·
Code Reusability
·
Fast Development
·
Avoids the use of scriptlet tags
90. What
are the different types of JSTL tags?
Answer – There are 5 types of JSTL tags –
Core Tags:
The JSTL core tags help in URL management, variable support,
flow control etc.
The prefix c used for core tags.
XML Tags:
The JSTL XML tags help in transformation, flow control etc.
The prefix x used for core tags.
Function Tags:
The JSTL function tags are used to provide support for string
length and string manipulation.
The prefix fn used for function tags.
SQL Tags:
The JSTL SQL tags are used to provide SQL support for the
development of JSP pages.
The prefix sql used for SQL tags.
Formatting Tags:
The JSTL formatting tags are used to provide support for
message, number, and date formatting etc.
The prefix fmt used for formatting tags.
91.
Have you ever heard about EL in JSP?
Answer – In JSP, EL means Expression Language. The EL is used in
order to make the objects accessibility simpler in JSP. The expression language
provides a number of objects such as session, sessionScope, applicationScope,
param, request, requestScope and many others. These objects can be directly
used in JSP in a simple manner.
92.
Differentiate between Java beans and Java
custom tags.
Answer – The difference between Java beans and Java custom tags
is as follows:
|
Java Beans
|
Java Custom Tags
|
|
Java beans cannot manipulate JSP content.
|
Java custom tags can manipulate JSP content.
|
|
It is simple to set up Java beans.
|
It is comparatively harder to set up Java custom tags.
|
|
Java beans are helpful to reduce the complex operations into
simpler form.
|
Java custom tags are helpful to reduce the complex operations
into simpler form.
|
|
Java beans is available in all 1.x versions of JSP.
|
Java custom tags can only be used in JSP 1.1
|
93.
Name the tags that are used in the development
of Java beans.
Answer – Three tags are used for the development of Java beans,
these are:
jsp:useBean
Jsp:getProperty
jsp:setProperty
94.
Write the statement that disables session in
JSP.
Answer – The statement that disables session in JSP is:
<%@ page session=“fasle” %>
95.
How are the context.getRequestDispatcher() and
request.getRequestDispatcher() different in terms of use?
Answer – In order to create context.getRequestDispatcher(path),
it relative path of the resource is required to be given while in order to
create request.getRequestDispatcher(path) absolute path of the resource is
required to be given alongwith.
96.
Name the directive used in JSP custom
tag. How will you perform the exception handling in JSP?
Answer – The directive used in JSP custom tag is JSP tag lib
directive.
The exceptions in JSP can be handled in two different ways:
1.
By the errorPage element of web.xml file
2.
By the errorPage element of page directive
97. What is
the use of JSP in MVC model?
Answer – JSP performs the role of the view in Model View
Controller. It is used for the purpose of presentation in MVC model. The MVC is
meant to deal with the calling of business classes and model to get the data.
After that, this received data is presented to JSP to render to the client.
98.
Name the various scope values for
<jsp:useBean> tag.
Answer – The scope value represents the bean scope i.e. scope of
the bean. There are four different scopes of the bean.
·
page
·
session
·
request
·
application
The default value of bean scope is page.
99.
Differentiate between include action and
include directive.
Answer – The difference between include action and include
directive is as follows:
|
Include Action
|
Include Directive
|
|
It includes content at the time of request.
|
It includes content at the time of page translation.
|
|
It does not include the original content.
|
It includes the original content.
|
|
Include action invokes the include( ) method of the Vendor
provided class.
|
Include directive doesn’t invoke any method.
|
|
Using include action is better for the dynamic pages.
|
Using include directive is better for the static pages.
|
100.
Did you find JSP technology extensible?
Answer – Yes, I found JSP technology extensible. The JSP
technology is considered extensible as it comes with custom tags or actions
that are encapsulated within tag libraries.
So here we reach the end of the Java interview questions blog.
The questions and answers covered in this Java Interview Questions blog are
the frequently-asked Java interview questions that the recruiters ask to
Java Professional in a Java interview. These are the Java Interview
Questions that will definitely help you ace your job interview.
The main difference is polymorphism is
a specific result of inheritance. Polymorphism is
where the method to be invoked is determined at runtime based on the type of
the object. This is a situation that results when you have one class inheriting from
another and overriding a particular method.
