Thread: Simple interface example giving erors

interface Test
{
 
       final static int a,b;
 
 
       int compute(int a,int b);
 
 
 
}
 
 
class Sum implements Test
{
 
public int compute()
 
      {
  System.out.println("Inside subclass");
 
 
 
 
 public int compute(int x, int y)
 
      {
  System.out.println("Inside subclass");
	return(x*y);
      }
 
 
 }
 
 
 
 
class Interfacedemo 
{
 
 public static void main(String args[])
  {
 
      System.out.println("Interface Example . . .");
 
 
 
      Test t;
 
      Sum s;
 
      t = s;
 
 
  System.out.println("Interface Example . . ." + t.compute(10,20));
 
 
   }
 
}

You forgot to post the full text of the error message.

C:\Users\Pushpendra\Desktop\Project\Interface>java c Interfacedemo.java
Interfacedemo.java:4: = expected
final static int a,b;
^
Interfacedemo.java:4: = expected
final static int a,b;
^
Interfacedemo.java:25: illegal start of expression
public int compute(int x, int y)
^
3 errors

C:\Users\Pushpendra\Desktop\Project\Interface>

Where did you get this example from?

final static int a,b;

Why do you have this statement in the interface?

Interfacedemo.java:25: illegal start of expression

The compiler is confused by what looks like the start of a new method within another method. You can not nest one method within another. Finish one with its ending } before starting another

This is how i wrote again the code . . . but it got failed to execute correctly.

interface Test
{
 
      final  int a;
      final   int b;
 
       int compute(int a,int b);
 
 
 
}
 
 
class Sum implements Test
{
 
 
 
   int compute(int x, int y)
 
      {
          System.out.println("Inside subclass");
 
	return(x*y);
      }
 
 
 }
 
 
 
 
class Interfacedemo 
{
 
 public static void main(String args[])
  {
 
      System.out.println("Interface Example . . .");
 
 
 
      Test t;
 
      Sum s;
 
      t = s;
 
 
 
  System.out.println("Interface Example . . ." + t.compute(10,20));
 
 
   }
 
 
}

__________________________________________________ __________________-

ERRORS
__________________________________________________ ______________________

Interfacedemo.java:4: = expected
final int a;
^
Interfacedemo.java:5: = expected
final int b;
^
2 errors

Interfacedemo.java:4: = expected

The compiler wants the variables to be assigned a value. That is done with the = followed by a value.
Have you read the Tutorial on how to write an interface:
Start here: // Trail: Learning the Java Language: Table of Contents (The Java™ Tutorials)
and find interface