java important theory problems

Question 03:

Which of the following identifiers are valid? Which are Java keywords?

miles, Test, a++, ––a, 4#R, $4, #44, apps

class, public, int, x, y, radius

Ans:

      The valid identifier are miles, Test, $4, apps, x, y, radius.

    Java keywords are int class public.

Question 04:

Identify and fix the errors in the following code:

 public class Test {

 public static void main(String[] args) {

 int i = k + 2;

 System.out.println(i);

 }

 }

Ans:

      A variable must be declared before it use variable k is not declared

Error in int i=k+2;   k is not declared.

Question 05:

 What are the benefits of using constants? Declare an int constant SIZE with value 20.

Ans:

 01 It is used for multiple times I  the program

02  Its value can be changed at single location

03 It make easy to understand the program