Java

Question 1

Why is the Java platform independent?

Answer 1

Java is called so because of its bytecode which can run on any system irrespective of its underlying operation system. The JVM provides a run-time environment in which java byte can be executed.

Question 2

What class is the superclass for every other class?

Answer 2

Object class.

Question 3

Why is Java not considered to be 100% object orientated?

Answer 3

Because it make use of eight primitive data types (boolean, byte, char, int, float, double, long, short) which are not objects.

Question 4

What does a constructor do in Java?

Answer 4

It is a block of code used to initialise an object. The keyword new class the constuctor.

Question 5

What is a singleton class?

Answer 5

Only one instance of a singleton class can be created at any given time. This is achieved by making the constructor private.

Question 6

What is a static method?

Answer 6

A static method belongs to the class rather than an object class. A static method can be invoked without the need for creating an instance of a class.

Question 7

What the four pillars of object orientation

Answer 7

Abstraction, Encapsulation, Inheritance, Polymorphism