An interface can inherit from another interface.
An interface can inherit from multiple interfaces.
For the following interface
interface Singer { void sing(); void setRate(double rate); double getRate(); } interface MySpecialSinger extends Singer { }
MySpecialSinger interface inherits the three abstract methods from the Singer interface.
Any class implementing the MySpecialSinger interface will need to implement those three methods.
interface Singer { void sing();//w w w. j a va2 s .c o m void setRate(double rate); double getRate(); } interface MySpecialSinger extends Singer { } class ASinger implements MySpecialSinger{ @Override public void sing() { } @Override public void setRate(double rate) { } @Override public double getRate() { return 0; } } public class Main { public static void main(String[] args) { } } interface Writer { void write(); void setRate(double rate); double getRate(); } interface Player { void play(); void setRate(double rate); default double getRate() { return 300.0; } }