Question

我最近在java中创建了一个MakeDots类，当你拖动鼠标时，它会产生点（是的！）。我实现了一个MouseMotionListener。它工作正常。然后我添加了一些按钮来改变点的颜色。我为此添加了ActionListeners。一旦我这样做，颜色变化起作用，但我只能画在按钮的非常小的边界！为什么会这样？我如何解决它？如果您需要我发布我的代码，请在评论中说明，我会这样做。

CODE：

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.applet.Applet;
import java.awt.Button;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;


public class MakeDots extends Applet implements MouseMotionListener{
    private Graphics graphics = null;
    private Color dotColor = Color.red;
    private Button setRed;
    private Button setPink;
    private Button setPurple;
    private Button clrBtn;
    public void init() {
        setRed = new Button("Red");
        setPink = new Button("Pink");
        setPurple = new Button("Purple");
        clrBtn = new Button("Clear");
        this.addMouseMotionListener(this);
        this.add(setRed);
        this.add(setPink);
        this.add(setPurple);
        this.add(clrBtn);
        setRed.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                dotColor = Color.red;
            }
        });
        setPink.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                dotColor = Color.pink;
            }
        });
        setPurple.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                dotColor = new Color(80, 0, 80);
            }
        });
        clrBtn.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e) {
                clear();
            }

        });
    }

    public void paint(Graphics g) {
        this.setSize(new Dimension(800, 600));
        graphics = g.create();
        clear();
    }
    public void drawDot(int x, int y) {
        graphics.setColor(dotColor);
        graphics.fillOval(x, y, 10, 10);
    }


    public void clear() {
        Dimension d = this.getSize();
        graphics.setColor(Color.WHITE);
        graphics.fillRect(0, 0, d.width, d.height);
    }


    @Override
    public void mouseDragged(MouseEvent e) {
            int mouseX = e.getX();
            int mouseY = e.getY();
            drawDot(mouseX, mouseY);
    }

    @Override
    public void mouseMoved(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }
}

Answer 1

您可能想做的事情很少。
每次添加actionPerformed(...)时都会失去写actionListener()的做法。只需使用getActionCommand()来检查触发事件的按钮。另外，创建一个Color()的全局对象，并在actionPerformed()

中更新它

为什么实现ActionListener会使applet缩小（虚拟）？

1 个答案: