java

Question 1

What are supported platforms by Java?

Answer 1

Mac OS, Windows, Linux, Unix

Question 2

List five features of Java

Answer 2

1 OOP
2 Robust 
3 Interpreted
4 Multithreaded
5 Multi Platform

Question 3

Why is Java Architecture neutral?

Answer 3

Its compiler creates an architecture neutral object file format..
The compiled source code can be executed on many preprocessors with Java runtime System.

Question 4

How does Java enables High Performance?

Answer 4

Java uses Just In Time Compiler. This compiler converters java bycode to machine specific instruction.

Question 5

List two Java IDE

Answer 5

Eclipse

Netbeans

Question 6

What is an object?

Answer 6

A runtime entity whose state is in stored in fields and whose behaviours is shown via the methods.

Question 7

What is a class?

Answer 7

A blueprint from which objects are created.

It contains the fields and methods to describe the state of the object.

Question 8

What type of variables can a class consists of ?

Answer 8

• Local
• Instance variable
• Class variables

Question 9

What is a local variable?

Answer 9

Variables created inside the method, blocks or constructors.

The variable will be created and initialized within this..

Question 10

What are instance variable

Answer 10

The variables created within a class but outside the method. These variables are instantiated when the class is loaded.

Question 11

When are the instance variables initialized?

Answer 11

when the class is loaded

Question 12

What is a class variable?

Answer 12

A variable created within a class but outside any methods and declared with a static keyword.

Question 13

What is singleton class

Answer 13

It controls object creation generally limiting the number to one but allowing the flexibility to change and allowing more creation of objects should they be required.

Question 14

What is a constructor?

Answer 14

Used to create an instance of a class.

Question 15

List three steps of creating an object?

Answer 15

1. Object is declared
2. Instantiated
3. Initialized

Question 16

What is the default for float/double datatype?

Answer 16

• 0.0f

- 0.0d

Question 17

What is a static variable?

Answer 17

Same as class variables. They are created within a class but outside methods, constructors, blocks with the static keyword.

Question 18

What is access modifier?

Answer 18

that controls access to classes, variables, methods, etc

Question 19

What is protected access modifier?

Answer 19

variables, methods and constructors which are declared protected can be accessed by the subclass of the other package and any class within the same package of the protected member’s class.

Question 20

What is synchronized ?

Answer 20

An modifier that controls an object’s access to shared resource.

Question 21

Which Operator is at the highest precedence?

Answer 21

()

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