JAVA使用EPLICSE编译时提示出错，求解

源代码：
package com.tarena.shoot;
import java.util.Random;
//Airplane----敌机既是飞行物，
public class Airplane extends FlyingObject implements Enemy{
private int speed = 2;//敌机走步的步数
public Airplane(){
image = ShootGame.airplane;
width = image.getWidth();
height = image.getHeight();
Random rand = new Random();
x = rand.nextInt(ShootGame.WIDTH - this.width);
y = -this.height; //y:负的敌机的高
}

//重写 getScore();
public int getScore(){
return 5;
}

public void step(){
y += speed;
}
public boolean outOfBounds(){
return this.y > ShootGame.HEIGHT; //敌机的y坐标大于窗口的高

}
}

提示出错：
FlyingObject 无法解析为类型
还有很多类似的出错，这是其中一个