Question

eclipse为什么显示不出来图片

package image;

import java.awt.*;
import javax.swing.*;
public class ImageTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
JFrame frame = new ImageFrame();
frame.setTitle("ImageTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
});
}
}

class ImageFrame extends JFrame
{
public ImageFrame()
{
add(new ImageComponent());
pack();
}
}

class ImageComponent extends JComponent
{
private static final int DEFAULT_WIDTH = 300;
private static final int DEFAULT_HEIGHT = 200;

private Image image;

public ImageComponent()
{
image = new ImageIcon("blue-ball.gif").getImage();
}

public void paintComponent(Graphics g)
{
if (image == null) return;

int imageWidth = image.getWidth(this);
int imageHeight = image.getHeight(this);

// draw the image in the upper-left corner

g.drawImage(image, 0, 0, null);
// tile the image across the component

for (int i = 0; i * imageWidth <= getWidth(); i++)
for (int j = 0; j * imageHeight <= getHeight(); j++)
if (i + j > 0)
g.copyArea(0, 0, imageWidth, imageHeight, i * imageWidth, j * imageHeight);
}

public Dimension getPreferredSize() { return new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT); }
}

为什么显示不出来图片，哪里出错了？

Answer 1

在paintComponent方法最后加上

SwingUtilities.updateComponentTreeUI (this);

即可