1 public class Something {2 void doSomething () 3 {4 private String s = "";5 int l = s.length();6 }7 }

1 interface Playable { 2 void play(); 3 } 4 interface Bounceable { 5 void play(); 6 } 7 interface Rollable extends Playable, Bounceable { 8 Ball ball = new Ball("PingPang"); 9 }10 class Ball implements Rollable {11 private String name;12 public String getName() {13 return name;14 }15 public Ball(String name) {16 this.name = name; 17 }18 public void play() {19 ball = new Ball("Football");20 System.out.println(ball.getName());21 }22 }

1 public class Something {2 public int addOne(final int x) {3 return ++x;4 }5 }

问题：1.局部变量前不能加修饰符 

2.在接口中定义的常量还是方法，前面都要修饰

3.被final修饰，不能被修改