Question

我想使用applet绘制多行复选框以选择行的颜色。这是我的代码：

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.util.Vector;

public class PaintApplet extends Applet implements MouseMotionListener,ItemListener{
    public void init() {

        setLayout(new GridLayout(1, 0));
        CheckboxGroup colorType = new CheckboxGroup();
        red = new Checkbox("red", colorType, false);
        red.addItemListener(this);
        green = new Checkbox("green", colorType, false);
        green.addItemListener(this);
        blue = new Checkbox("blue", colorType, true);
        blue.addItemListener(this);

        //setLayout(new GridLayout(0, 1));

        Panel p = new Panel();
        add(p);
        p.add(red);
        p.add(green);
        p.add(blue);

        addMouseMotionListener(this);
    }

    public void itemStateChanged(ItemEvent e) {
        if (e.getSource() == red)
           System.out.println("red");
        else if (e.getSource()==green)
            System.out.println("green");
        else if (e.getSource()==blue)
            System.out.println("blue");
    }

    public void mouseDragged(MouseEvent e) {
        draw=true;
       // X=new Vector<Integer>();
       // Y=new Vector<Integer>();
        X.add(e.getX());
        Y.add(e.getY());
        System.out.println("mouse is being dragged at location (" + e.getX() + ", " + e.getY() + ")");
        DrawX.add(X.get(lastSize));
        DrawY.add(Y.get(lastSize));
        DrawX.add(X.get(X.size()-1));
        DrawY.add(Y.get(Y.size()-1));
        repaint();
        lastSize=X.size();
        //System.out.println(lastSize);
    }

    public void mouseMoved(MouseEvent e) {
        //System.out.println("mouse is being moved at location (" + e.getX() + ", " + e.getY() + ")");
    }


    public void paint(Graphics g) {
        for(int i=0;i<X.size()-1;i=i+2)
        {
                initX=DrawX.get(i);
                initY=DrawY.get(i);
                finalX=DrawX.get(i+1);
                finalY=DrawY.get(i+1);
                //g.drawLine(0, 0, 100, 100);
                if(draw)
        g.drawLine(initX, initY, finalX, finalY);
        g.setColor(Color.blue);
           //System.out.println(initX);
           //System.out.println(finalY); 
        }
           super.paint(g);
           //repaint();

    }

    int lastSize=0;
    int initX,initY;
    int finalX,finalY;
    Vector<Integer> X=new Vector<Integer>();
    Vector<Integer> Y=new Vector<Integer>();
    boolean draw=false;
    Vector<Integer> DrawX=new Vector<Integer>();
    Vector<Integer> DrawY=new Vector<Integer>();
    Checkbox red,green,blue;
}

然而，代码的问题在于，当正确显示复选框时，拖动鼠标时无法绘制线条，但在删除复选框时，线条绘制功能正常工作。我实现MouseMotionListener和ItemListener时有什么问题吗？

Answer 1

您可以尝试将两个侦听器放在两个separeted线程中。 Here is how to set up a thread

使用这种方法，两个侦听器可以分别同时工作，因此它们不会相互阻塞。

Applet MouseMotionListener和Itemlistener发生冲突？

1 个答案: