Toy Program 2

查错：

interface Playable {
	void play();
}

interface Bounceable {
	void play();
}

interface Rollable extends Playable, Bounceable {
	Ball ball = new Ball("PingPang");
}

public 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());
	}
}

 "interface Rollable extends Playable, Bounceable "没有问题，interface可以继承多个intefaces。

 

问题出在interface Rollable里的"Ball ball = new Ball("PingPang");"。

HINT：任何在interface里声明的interface variable (接口变量，也可称成员变量)，默认为public static final。