#1 Random Questions for practice on Basic Java Programing

 Random Questions for practice on Basic Java Programing

Given below is a comprehensive list of the most important and commonly asked basic and advanced Java programming interview questions with detailed answers.

Q #1) What is JAVA?

Answer: Java is a high-level programming language and is platform-independent.

Java is a collection of objects. It was developed by Sun Microsystems. There are a lot of applications, websites, and games that are developed using Java.

Q #2) What are the features of JAVA?

Answer: Features of Java are as follows:

• OOP concepts

·         Object-oriented

·         Inheritance

·         Encapsulation

·         Polymorphism

·         Abstraction

• Platform independent: A single program works on different platforms without any modification.
• High Performance: JIT (Just In Time compiler) enables high performance in Java. JIT converts the bytecode into machine language and then JVM starts the execution.
• Multi-threaded: A flow of execution is known as a Thread. JVM creates a thread which is called the main thread. The user can create multiple threads by extending the thread class or by implementing the Runnable interface.

Q #3) How does Java enable high performance?

Answer: Java uses Just In Time compiler to enable high performance. It is used to convert the instructions into bytecodes.

Q #4) Name the Java IDE’s?

Answer: Eclipse and NetBeans are the IDE’s of JAVA.

Q #5) What do you mean by Constructor?

Answer: Constructor can be explained in detail with enlisted points:

• When a new object is created in a program a constructor gets invoked corresponding to the class.
• The constructor is a method which has the same name as the class name.
• If a user doesn’t create a constructor implicitly a default constructor will be created.
• The constructor can be overloaded.
• If the user created a constructor with a parameter then he should create another constructor explicitly without a parameter.

Q #6) What is meant by the Local variable and the Instance variable?

Answer:

Local variables are defined in the method and scope of the variables that exist inside the method itself.

Instance variable is defined inside the class and outside the method and the scope of the variables exists throughout the class.

Q #7) What is a Class?

Answer: All Java codes are defined in a Class. It has variables and methods.

Variables are attributes which define the state of a class.

Methods are the place where the exact business logic has to be done. It contains a set of statements (or) instructions to satisfy the particular requirement.

Example:

public class Addition{ //Class name declaration int a = 5; //Variable declaration int b= 5; public void add(){ //Method declaration int c = a+b; } }

Q #8) What is an Object?

Answer: An instance of a class is called an object. The object has state and behavior.

Whenever the JVM reads the “new()” keyword then it will create an instance of that class.

Example:

public class Addition{ public static void main(String[] args){ Addion add = new Addition();//Object creation } }

The above code creates the object for the Addition class.

Q #9)What is statements in java?

Answer: there are 3 types of statement in java:

• if- else
• switch case

if -else

 :- -> 1 its a conditional statement having in the block and code

                -> is execute when the statement is true.

                -> is false then executes else statement

ie,->

public class Addition{ //Class name declaration int a = 5; //Variable declaration int b= 5; public void add(){ //Method declaration if(a!=0){//statement is true then it will  be executes int c = a+b; }else{ System.out.println("it is negative value"); } }} switch() statement  :- -> 1 its a conditional statement having in the block and code                 -> is execute when the statement is match to given case.                 -> is false then executes default statement ie,-> public class Addition{ //Class name declaration int a = 5; //Variable declaration int b= 5; ie. take arithmetic operation Scaner sc = new Scaner(System.in); //scanner class for input String opp = sc.next(); switch(opp ){ // syntax for switch case case add : public void add(){ //Method declaration int c = a+b; break; case sub: public void add(){ //Method declaration int c = a-b; break; defoult: // defoult value System.out.println("please choose operation"); } }}}

Q #10)What are the OOPs concepts?

Answer: OOPs concepts include:

• Inheritance
• Encapsulation
• Polymorphism
• Abstraction
• Interface

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