1

我有一个 JButton，可以根据情况选择 2 个不同的 imageIcons 设置。

image1Url = getClass().getResource(filename1);
image2Url = getClass().getResource(filename2);
ImageIcon image1 = new ImageIcon( image1Url , "image1")
ImageIcon image2 = new ImageIcon( image2Url , "image2")

JButton button = new JButton;

//Either image1 or image2 is set to this button depending 
//on whether the user clicks this button or whether the 
//computer sets an image there. The point is that the programme 
//then needs to respond depending upon what the image on the button is.
//I tried using...

if(button.getIcon() ==image1)
{
    //respond appropriately.
}

然而这并没有奏效。有人可以向我解释为什么这不起作用以及是否有其他方法可以解决这个问题？我想我也许可以使用图像描述，但不知道如何实现这一点。谢谢

4

2 回答 2

4

我不建议您使用==，因为您正在比较参考资料。当然，除非那是你想要做的。

我想说最简单的方法是设置一个值（例如 a boolean）来确定ImageIcon当前使用的内容，然后与之进行比较。

编辑 对不起，我实际上误解了这个问题。如果您想使用描述进行比较，只需执行以下操作：

String desc = ((ImageIcon)button.getIcon()).getDescription();
if(desc.equals(image1.getDescription())
{
    //descriptions are the same
}
于 2012-11-04T16:14:16.517 回答
2

  • 对我有用，一定还有另一个问题，

  • 确保该图标必须是 ImageIcon 的实例，必须在您的代码中进行测试

例子

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.swing.*;

public class JButtonAndIcon {

    private static JButton label = new JButton();
    private static Random random = new Random();
    private static ImageIcon image1; // returns null don't worry about
    private static ImageIcon image2; // returns null don't worry about
    private static Timer backTtimer;
    private static int HEIGHT = 300, WEIGHT = 200;

    public static void main(String[] args) throws IOException {
        label.setPreferredSize(new Dimension(HEIGHT, WEIGHT));
        final JButton button = new JButton("Push");
        label.setBorderPainted(false);
        label.setBorder(null);
        label.setFocusable(false);
        label.setMargin(new Insets(0, 0, 0, 0));
        label.setContentAreaFilled(false);
        //button.setLayout(new BorderLayout());
        //button.add(label);
        button.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                if (label.getIcon() == image1) {
                    label.setIcon(image2);
                } else {
                    label.setIcon(image1);
                }
            }
        });
        JFrame frame = new JFrame("Test");
        frame.add(label);
        frame.add(button, BorderLayout.NORTH);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        startBackground();
        frame.setVisible(true);
    }

    private static void startBackground() {
        backTtimer = new javax.swing.Timer(2000, updateBackground());
        backTtimer.start();
        backTtimer.setRepeats(true);
    }

    private static Action updateBackground() {
        return new AbstractAction("Background action") {

            private static final long serialVersionUID = 1L;

            @Override
            public void actionPerformed(ActionEvent e) {
                image1 = new ImageIcon(getImage());
                label.setIcon(image1);
            }
        };
    }

    public static BufferedImage getImage() {
        int w = label.getWidth();
        int h = label.getHeight();
        GradientPaint gp = new GradientPaint(0f, 0f, new Color(
                127 + random.nextInt(128),
                127 + random.nextInt(128),
                127 + random.nextInt(128)),
                w, w,
                new Color(random.nextInt(128), 
                random.nextInt(128), random.nextInt(128)));
        BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2d = bi.createGraphics();
        g2d.setPaint(gp);
        g2d.fillRect(0, 0, w, h);
        g2d.setColor(Color.BLACK);
        g2d.dispose(); // thanks notified by @trashgod
        return bi;
    }
}
于 2012-11-04T16:21:16.427 回答