如何在java Graphics中检查按钮颜色是否与正方形颜色相同并增加点数

Question

我正在尝试创建一个游戏，其中有 2 个按钮 red 和 blue。正方形从 Color 数组中随机选择一种颜色。因此，如果我们按下 2 个按钮中的任何一个，并且该按钮的颜色与方块中的随机颜色相同，我们就会得分。这是我的代码-

import java.awt.Button;
import java.awt.Color;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.TextArea;
import java.awt.TextField;
import java.awt.event.*;
import java.util.Random;

import javax.swing.JLabel;
import javax.swing.JTextArea;  
class apple1 extends Frame implements ActionListener{
    private Button b;

    public apple1(){  


        tf = new TextField("Points: ");
        tf.setBounds(10, 30, 140, 20);

        //create components   
        b=new Button("RED");
        b.setBackground(Color.red);
        b.setBounds(80,260,80,30); 


        Button b2=new Button("BLUE");
        b2.setBackground(Color.blue);
        b2.setBounds(180,260,80,30); 

        //register listener
        b.addActionListener(this);//passing current instance  

        //add components and set size, layout and visibility  
        add(tf);add(b);add(b2);  
        setSize(600,600);  
        setLayout(null);
        setVisible(true);
        }

TextField tf;
JTextArea lbl;
    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;
        Color[] clrs = {Color.red,Color.blue};
        Random rand = new Random();
        g2.setColor(clrs[rand.nextInt(clrs.length)]);
        g2.fillRect (60, 50, 200, 200);
        if(g2.getColor().equals(b.getBackground())){
            int count = 0;
            tf.setText(String.valueOf(count++));
        }
      }

public void actionPerformed(ActionEvent e){
    repaint();
}  
public static void main(String args[]){  
new apple1();  
}  
}

这是我在 eclipse 中遇到的错误：线程异常 "AWT-EventQueue-0" java.lang.NullPointerException 在 apple1.paint(apple1.java:53) 在 sun.awt.RepaintArea.paintComponent(RepaintArea.java:264) 在 sun.lwawt.LWRepaintArea.paintComponent(LWRepaintArea.java:59) 在 sun.awt.RepaintArea.paint(RepaintArea.java:240) 在 sun.lwawt.LWComponentPeer.handleJavaPaintEvent(LWComponentPeer.java:1314) 在 sun.lwawt.LWComponentPeer.handleEvent(LWComponentPeer.java:1198) 在 java.awt.Component.dispatchEventImpl(Component.java:4965) 在 java.awt.Container.dispatchEventImpl(Container.java:2294) 在 java.awt.Window.dispatchEventImpl(Window.java:2746) 在 java.awt.Component.dispatchEvent(Component.java:4711) 在 java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758) java.awt.EventQueue.access500 美元（EventQueue.java:97）在 java.awt.EventQueue$3.run(EventQueue.java:709) 在 java.awt.EventQueue$3.run(EventQueue.java:703) 在 java.security.AccessController.doPrivileged（本机方法）在 java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) 在 java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86) 在 java.awt.EventQueue$4.run(EventQueue.java:731) 在 java.awt.EventQueue$4.run(EventQueue.java:729) 在 java.security.AccessController.doPrivileged（本机方法）在 java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) 在 java.awt.EventQueue.dispatchEvent(EventQueue.java:728) 在 java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201) 在 java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116) 在 java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105) 在 java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) 在 java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93) 在 java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

Random Color Color Compare

我正处于开发这个所谓游戏的初始阶段，但我认为我无法获得在 b 按钮的 actionPerformed() 方法中调用的 g2 Graphics 变量。请帮忙。

Answer 1

您应该从构造函数中删除声明：

class apple1 extends Frame implements ActionListener {

private Button b;

TextField tf;
JTextArea lbl;
int count = 0;

public apple1() {

    tf = new TextField("Points: ");
    tf.setBounds(10, 30, 140, 20);

    //create components   
    b = new Button("RED");
    b.setBackground(Color.red);
    b.setBounds(80, 260, 80, 30);

    Button b2 = new Button("BLUE");
    b2.setBackground(Color.blue);
    b2.setBounds(180, 260, 80, 30);

    //register listener
    b.addActionListener(this);//passing current instance  

    //add components and set size, layout and visibility  
    add(tf);
    add(b);
    add(b2);
    setSize(600, 600);
    setLayout(null);
    setVisible(true);
}

public void paint(Graphics g) {
    Graphics2D g2 = (Graphics2D) g;
    Color[] clrs = {Color.red, Color.blue};
    Random rand = new Random();
    g2.setColor(clrs[rand.nextInt(clrs.length)]);
    g2.fillRect(60, 50, 200, 200);
    if (g2.getColor().equals(b.getBackground())) {
        tf.setText(String.valueOf(count++));
    }
}

public void actionPerformed(ActionEvent e) {
    repaint();
}

public static void main(String args[]) {
    new apple1();
}
}

Answer 2

count 应该像这样在 paint 函数之外声明

class Apple1 extends Frame implements ActionListener {

private Button b;
TextField tf;
JTextArea lbl;
int count = 0;

public Apple1() {
    tf = new TextField("Points: ");
    tf.setBounds(10, 30, 140, 20);
    //create components   
    b = new Button("RED");
    b.setBackground(Color.red);
    b.setBounds(80, 260, 80, 30);

    Button b2 = new Button("BLUE");
    b2.setBackground(Color.blue);
    b2.setBounds(180, 260, 80, 30);

    //register listener
    b.addActionListener(this);//passing current instance  

    //add components and set size, layout and visibility  
    add(tf);
    add(b);
    add(b2);
    setSize(600, 600);
    setLayout(null);
    setVisible(true);
}

public void paint(Graphics g) {
    Graphics2D g2 = (Graphics2D) g;
    Color[] clrs = {Color.red, Color.blue};
    Random rand = new Random();
    g2.setColor(clrs[rand.nextInt(clrs.length)]);
    g2.fillRect(60, 50, 200, 200);
    if (g2.getColor().equals(b.getBackground())) {
        tf.setText(String.valueOf(count++));
    }
}

 public void actionPerformed(ActionEvent e) {
    repaint();
}

public static void main(String args[]) {
    new Apple1();
}
}

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