public class Computer implements Device, Action{  public void doIt() { System.out.println("");} }abstract class Phone1 extends Computer { }abstract class Phone2 extends Computer{  public void doIt(int x) { }}class Phone3 extends Computer implements Device{ public void doStuff() { } }interface Device { public void doIt(); String ACTION="DEVICE";}interface Action { public void doIt(); String ACTION = "TEST1";}

如果接口实现了相同的变量,则子类不调用该变量时可编译通过,但是如果调用则报ambigous错误.