不能在 2 个数组列表上使用 equal

Question

所以我有这 2 个 ArrayLists 一个用于球，另一个用于敌人。我想当球的 x 和 y 坐标等于敌人的 x 和 y 坐标时，它们都被删除。这是代码：

主要：

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;

public class Main extends JPanel implements ActionListener, KeyListener{
Timer t = new Timer(5,this);
public JFrame f;
public Paint p;
public Ball ball;
public Enemy enemy;
public static Main main;
private boolean s1 = false, s2 = false, s3 = false;

public Main (){
    f = new JFrame();
    f.setSize(500,500);
    f.setBackground(new Color(32768));
    f.setVisible(true);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.add(p = new Paint());
    f.addKeyListener(this);
    f.setResizable(false);
    t.start();

}
public void actionPerformed(ActionEvent arg0) {
    p.color++;
    p.c++;
    p.move();
    p.repaint();
}

public void keyPressed(KeyEvent arg0) {
    if (arg0.getKeyCode() == KeyEvent.VK_A)
    {
        p.velx = -1;
        s1 = true;
    }
    if (arg0.getKeyCode() == KeyEvent.VK_D)
    {
        p.velx = 1;
        s2 = true;
    }
    if (arg0.getKeyCode() == KeyEvent.VK_SPACE){
        p.al.add(new Ball(p.x +30,p.y2));
        s3 = true;
    }
    if(s1==true && s3==true)
    {
        p.velx = -1;
        p.al.add(new Ball(p.x +30,p.y2));
    }
    if(s2==true && s3==true)
    {
        p.velx = 1;
        p.al.add(new Ball(p.x +30,p.y2));
    }
    if (s3 == true){
        p.al.add(new Ball(p.x +30,p.y2));
    }
}

public void keyReleased(KeyEvent arg0) {
        if (arg0.getKeyCode() == KeyEvent.VK_A)
        {
            p.velx = 0;
            s1 = false;
        }
        if (arg0.getKeyCode() == KeyEvent.VK_D)
        {
            p.velx = 0;
            s2 = false;
        }
        if (arg0.getKeyCode() == KeyEvent.VK_SPACE){
            s3 = false;
        }
}

public void keyTyped(KeyEvent arg0) {

}

public static void main(String[] args){
    main = new Main();
}
}

绘画：

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Random;

import javax.swing.JPanel;
import javax.swing.Timer;
public class Paint extends JPanel implements ActionListener{
Timer t = new Timer(5,this);
public int x = 250, y = 450, velx = 0, color = 1,vely = -1,y2 = y, c = 32768, velz = 1;
public ArrayList<Ball> al = new ArrayList<Ball>();
public ArrayList<Enemy> al2 = new ArrayList<Enemy>();
Random rx = new Random();
Random ry = new Random();
public Enemy enemy;
public Ball ball;

public Paint(){
    createEnemys();
}

ActionListener taskPerformer = new ActionListener(){
    public void actionPerformed(ActionEvent arg0) {
        Iterator<Enemy> it = al2.iterator();
        while (it.hasNext()) {
            Enemy enemy = it.next();
            if (enemy.x == 520)
            {
                enemy.x = -120;
            }
            enemy.x +=1;
            repaint();
        }
    }
};
Timer t2 = new Timer(5,taskPerformer);

public void actionPerformed(ActionEvent arg0) {
    Iterator<Ball> it = al.iterator();
    while (it.hasNext()) {
        Ball ball = it.next();
        if (ball.y < -10) {
            it.remove();
            System.out.println(enemy.getX());
        } else {
            ball.y += vely;
            repaint();
        }
    }
}

public void paintComponent(Graphics g){
    super.paintComponent(g);
    g.setColor(Color.gray);
    g.fillRect(0, 0, 500, 500);
    for(Ball ball : this.al) {
        g.setColor(Color.RED);
        g.fillOval(ball.x,ball.y,10,10);
        t.start();
    }
    for(Enemy enemy : this.al2) {
        g.setColor(new Color(c));
        g.fillRect(enemy.x,enemy.y,enemy.h,enemy.w);
        t2.start();
    }
    g.setColor(new Color(color));
    g.fillRect(x, y, 70, 10);
}



public void move(){
    x += velx;
    if (x <= 3)
    {
        x = 3;
    }
    if (x >= 420)
    {
        x = 420;
    }
}

public void createEnemys(){
    al2.add(new Enemy(-60,10,60,10));
    al2.add(new Enemy(20,10,60,10));
    al2.add(new Enemy(100,10,60,10));
    al2.add(new Enemy(180,10,60,10));
    al2.add(new Enemy(260,10,60,10));
    al2.add(new Enemy(340,10,60,10));
    al2.add(new Enemy(420,10,60,10));
    al2.add(new Enemy(500,10,60,10));

    al2.add(new Enemy(-60,30,60,10));
    al2.add(new Enemy(20,30,60,10));
    al2.add(new Enemy(100,30,60,10));
    al2.add(new Enemy(180,30,60,10));
    al2.add(new Enemy(260,30,60,10));
    al2.add(new Enemy(340,30,60,10));
    al2.add(new Enemy(420,30,60,10));
    al2.add(new Enemy(500,30,60,10));

    al2.add(new Enemy(-60,50,60,10));
    al2.add(new Enemy(20,50,60,10));
    al2.add(new Enemy(100,50,60,10));
    al2.add(new Enemy(180,50,60,10));
    al2.add(new Enemy(260,50,60,10));
    al2.add(new Enemy(340,50,60,10));
    al2.add(new Enemy(420,50,60,10));
    al2.add(new Enemy(500,50,60,10));

    al2.add(new Enemy(-60,70,60,10));
    al2.add(new Enemy(20,70,60,10));
    al2.add(new Enemy(100,70,60,10));
    al2.add(new Enemy(180,70,60,10));
    al2.add(new Enemy(260,70,60,10));
    al2.add(new Enemy(340,70,60,10));
    al2.add(new Enemy(420,70,60,10));
    al2.add(new Enemy(500,70,60,10));
}

}

球：

import javax.swing.JPanel;

public class Ball extends JPanel{
public int x,y;
public Ball(int x1, int y1) {
    x = x1;
    y = y1;
}
}

最后是敌人：

import javax.swing.JPanel;

public class Enemy extends JPanel{
public int x,y,h,w;
public Enemy(int x, int y,int h,int w) {
    this.x = x;
    this.y = y;
    this.h = h;
    this.w = w;
}
public int getX() {
    return x;
}
public int getY() {
    return y;
}
}

问题出在 Class Paint 中，我无法检查球与敌人的碰撞，因此无法将它们移除。如果有人可以帮助我谢谢

Answer 1

假设您使用 Java 8，可以使用 Stream API 和方法 removeAll(Collection) 来删除所有匹配的元素：

al.removeAll(
    al.stream().filter(
        ball -> {
            List<Enemy> enemies = al2.stream()
                .filter(enemy -> ball.x == enemy.x && ball.y == enemy.y)
                .collect(Collectors.toList());
            al2.removeAll(enemies);
            return !enemies.isEmpty();
        }
    ).collect(Collectors.toList())
);

否则，由于 remove()[=20= 方法，您仍然可以使用 2 loops 的旧方法迭代 Iterator 以能够删除当前元素]

main: for (Iterator<Ball> itBall = al.iterator(); itBall.hasNext();) {
    Ball ball = itBall.next();
    for (Iterator<Enemy> itEnemy = al2.iterator(); itEnemy.hasNext();) {
        Enemy enemy = itEnemy.next();
        if (ball.x == enemy.x && ball.y == enemy.y) {
            itBall.remove();
            itEnemy.remove();
            continue main;
        }
    }
}

不能在 2 个数组列表上使用 equal

Can't use equal on 2 arraylists

java

android

arraylist

jpanel

jframe