java - JApplet - 当 boolean 值为 true 时不会绘制图像

Question

我有 4 个图 block :蓝色、红色、绿色和黄色。当鼠标移到图 block 上时，我希望它亮起(只需将图像更改为浅色图像)。相反，什么也没有发生。

我已经做了一些简单的调试，并且知道图像已正确导入并且 mouseOverTile[0] 变为 true。

import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.Arrays;

import javax.swing.ImageIcon;
import javax.swing.JApplet;


public class MainGame extends JApplet implements MouseListener, Runnable
{
    private static final long serialVersionUID = 1L;
    Thread animator = null;
    Image blue, blueLit, red, redLit, green, greenLit, yellow, yellowLit;
    boolean takingTurn;
    boolean[] mouseOverTile = new boolean[4];

    public void init()
    {
        setSize(500, 500);

        blue = new ImageIcon("Images/Blue.png").getImage();
        blueLit = new ImageIcon("Images/Blue_Lit.png").getImage();
        red = new ImageIcon("Images/Red.png").getImage();
        redLit = new ImageIcon("Images/Red_Lit.png").getImage();
        green = new ImageIcon("Images/Green.png").getImage();
        greenLit = new ImageIcon("Images/Green_Lit.png").getImage();
        yellow = new ImageIcon("Images/Yellow.png").getImage();
        yellowLit = new ImageIcon("Images/Yellow_Lit.png").getImage();
        Arrays.fill(mouseOverTile, false);
        takingTurn = true;
        addMouseListener(this);
    }

    public void start()
    {
        if(animator == null)
        {
            animator = new Thread(this);
        }
    }

    public void stop()
    {
        animator = null;
    }

    @Override
    public void run() 
    {       
        while(Thread.currentThread() == animator)
        {
            try
            {
                Thread.sleep(1);
                repaint();
            }
            catch(Exception e)
            { }
        }
    }

    public void paint(Graphics g)
    {
        if(!mouseOverTile[0])
        {
            g.drawImage(blue, 50, 50, this);
        } else g.drawImage(blueLit, 50, 50, this);
        if(!mouseOverTile[1])
        {
            g.drawImage(red, 260, 50, this);
        } else g.drawImage(redLit, 260, 50, this);
        if(!mouseOverTile[2])
        {
            g.drawImage(green, 50, 260, this);
        } else g.drawImage(greenLit, 50, 260, this);
        if(!mouseOverTile[3])
        {
            g.drawImage(yellow, 260, 260, this);
        } else g.drawImage(yellowLit, 260, 260, this);
    }


    @Override
    public void mouseClicked(MouseEvent e) 
    {
        System.out.println("Mouse X: " + e.getX());
        System.out.println("Mouse Y: " + e.getY());
    }

    @Override
    public void mouseEntered(MouseEvent e) 
    {
        if(takingTurn)
        {
            if(e.getX() > 50 && e.getX() < 250)
            {
                mouseOverTile[0] = true;
                System.out.println(mouseOverTile[0]);
            }
        }
    }

    @Override
    public void mouseExited(MouseEvent e) 
    {
        if(takingTurn)
        {
            if(e.getX() < 50 || e.getX() > 250)
            {
                mouseOverTile[0] = false;
                System.out.println(mouseOverTile[0]);
            }
        }
    }

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

    }


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

    }

}

Answer 1

您尚未更新 View 。
当您进行一些更改时，调用repaint()。
例如，在 mouseEntered(...) 内的代码中:

@Override
public void mouseEntered(MouseEvent e) 
{
    if(takingTurn)
    {
        if(e.getX() > 50 && e.getX() < 250)
        {
            mouseOverTile[0] = true;
            System.out.println(mouseOverTile[0]);
            repaint();
        }
    }
}