GFX.java:37出错

Question

我正在尝试做碰撞，我以为我得到了它，但显然没有，所以当我运行我的游戏时，我得到了一个错误。这真的很烦人。所以我来这里寻求一些帮助:D希望:P不管怎样，我一直收到这个错误

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at com.shiny21.graphics.GFX.step(GFX.java:37)
    at com.shiny21.graphics.GFX.actionPerformed(GFX.java:65)
    at javax.swing.Timer.fireActionPerformed(Unknown Source)
    at javax.swing.Timer$DoPostEvent.run(Unknown Source)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$200(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

我还不能真正理解错误，但下面是代码GFX：

    package com.shiny21.graphics;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JPanel;
import javax.swing.Timer;

import com.shiny21.framework.Collision;
import com.shiny21.players.PlayerB;
import com.shiny21.players.PlayerR;

public class GFX extends JPanel implements ActionListener{

    PlayerR red;
    PlayerB blue;
    Collision col;

    public GFX(){

        red = new PlayerR(getX(), getY());
        blue = new PlayerB(getX(), getY());

        this.setFocusable(true);
        this.requestFocus();

        setBackground(Color.BLACK);

        Timer timer = new Timer(1000 / 60, this);
        timer.start();
    }

    public void step(){

        col.CollisionStep();
        red.step();
        blue.step();
        //System.out.println("");

    }

    public void paintComponent(Graphics g){
        super.paintComponent(g);

        //RED
        g.setColor(Color.RED);
        g.fillRect(red.getX(), red.getY(), 8, 8);

        g.setColor(Color.WHITE);
        g.drawRect(red.getX()+20 - red.getSightW(), red.getY()+20 - red.getSightH(), red.getSightW(), red.getSightH());

        //BLUE
        g.setColor(Color.BLUE);
        g.fillRect(blue.getX(), blue.getY(), 8, 8);

        g.setColor(Color.GREEN);
        g.drawRect(blue.getX()+20 - blue.getSightW(), blue.getY()+20 - blue.getSightH(), blue.getSightW(), blue.getSightH());

    }


    public void actionPerformed(ActionEvent ae) {
        step();
        repaint();
    }
}

这就是碰撞代码：

    package com.shiny21.framework;

import java.awt.Rectangle;

import com.shiny21.players.PlayerB;
import com.shiny21.players.PlayerR;

public class Collision {

    PlayerB blue;
    PlayerR red;

    public Collision(){
        CollisionStep();
    }

    public void CollisionStep(){
        Rectangle r1 = blue.getBounds();
        Rectangle r2 = red.getBounds();

        if(r1.intersects(r2)){
            blue.setDX(-1);
            red.setDX(1);
        }
    }
}

编辑1：

我现在得到了这个错误

Exception in thread "main" java.lang.NullPointerException
at com.shiny21.framework.Collision.<init>(Collision.java:14)
at com.shiny21.graphics.GFX.<init>(GFX.java:25)
at com.shiny21.framework.Game.main(Game.java:18)

然后我将这个添加到Collision类：

blue = new PlayerB(blue.getX(), blue.getY());
red = new PlayerR(red.getX(), red.getY());

Answer 1

您的字段col为空，并且从未设置。这一行col.CollisionStep();