Interface Variables

Interface Variables 

• An interface can contain variables the main purpose of these variables is to specify.
• Every interface variable is always public, static, final whether we are declaring or not. 

E.g

interface Interf {
   int x = 10;
}

public: To make this variable available for every implementation class

static: Without existing object also implementation class can access this variable

final:Implementation class can access this variable but cannot modify

Hence inside interface the following declaration are valid and equal

int x = 10;
public int x = 10;
public static int x = 10;
public static final int x = 10;
public static int x = 10;
final int x = 10;
public final int x = 10;
static final int x = 10;

As interface variables are public, static and final we cannot declare with following modifiers

1. private
2. protected
3. <default>
4. transient
5. volatile

Inside implementation classes we can access interface variables but we can’t modify their values.

interface Interf {
   int x = 10;
}

class Test implements Interf {
   public static void main(String args[]) {
      x = 888; //C.E
      System.out.println(x);
   }
}