结对review

public class Something {
void doSomething () 
{
private String s = "";
int l = s.length();
}
}

interface Playable {
void play();
}
interface Bounceable {
void play();
}
interface Rollable extends Playable, Bounceable {
Ball ball = new Ball("PingPang");
}
class Ball implements Rollable {
private String name;
public String getName() {
return name;
}
public Ball(String name) {
this.name = name; 
}
public void play() {
ball = new Ball("Football");
System.out.println(ball.getName());
}
}

public class Something {
public int addOne(final int x) {
return ++x;
}
}

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