Interface in java 2

Why do we use interface ?

• It is used to achieve total abstraction.
• Since java does not support multiple inheritance in case of class, but by using interface it can achieve multiple inheritance .
• It is also used to achieve loose coupling.
• Interfaces are used to implement abstraction. So the question arises why use interfaces when we have abstract classes?
  The reason is, abstract classes may contain non-final variables, whereas variables in interface are final, public and static.

interface in1 

{ 

// public, static and final 

final int a = 10; 

// public and abstract 

void display(); 

} 

// A class that implements interface. 

class testClass implements in1 

{ 

// Implementing the capabilities of 

// interface. 

public void display() 

{ 

System.out.println("Java"); 

} 

// Driver Code 

public static void main (String[] args) 

{ 

testClass t = new testClass(); 

t.display(); 

System.out.println(a); 

} 

} 

Java
10