重绘的JPanel不JApplet的工作 [英] Repaint JPanel doesn't work in JApplet
问题描述
我有主的JPanel(在JApplet的),它containts孩子的JPanel和按钮。我想点击该按钮,使孩子的JPanel移除,另一个孩子的JPanel添加到主的JPanel,但问题是,只有当我reclick按钮或调整JApplet的大小老二的JPanel AP $ P $相提并论呢。
I have the the main JPanel (in JApplet ) which containts the child JPanel and the button. I want to click the button make the child JPanel removed and another child JPanel added to the main JPanel, but the problem is that only when I reclick the button or adjust the JApplet's size the second child JPanel apprear then.
我的按钮的监听器:
button.addActionListener(new ActionListener(){
@Override
public void actionPerformed(ActionEvent e) {
panel.remove(custompanel);
panel.add(new CustomPanel("/hinhtu2.jpg"), BorderLayout.CENTER);
panel.repaint();
panel.revalidate();
}
});
我的整个code:
My whole code :
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class applet extends JApplet {
public void init() {
try {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createGUI();
}
});
} catch (Exception e) {
//System.err.println("createGUI didn't successfully complete");
e.printStackTrace();
}
}
private void createGUI() {
final JPanel panel = new JPanel(new BorderLayout());
JButton button = new JButton("CLICK ME");
panel.add(button, BorderLayout.SOUTH);
final CustomPanel custompanel = new CustomPanel("/hinhtu.jpg");
panel.add(custompanel, BorderLayout.CENTER);
button.addActionListener(new ActionListener(){
@Override
public void actionPerformed(ActionEvent e) {
panel.remove(custompanel);
panel.add(new CustomPanel("/hinhtu2.jpg"), BorderLayout.CENTER);
panel.repaint();
panel.revalidate();
}
});
add(panel);
}
public class CustomPanel extends JPanel{
String resource;
public CustomPanel(String resource){
super();
this.resource = resource;
}
public void paintComponent(Graphics g) {
Image x = Toolkit.getDefaultToolkit().getImage(getClass().getResource(resource));
g.drawImage(x, 0, 0, null);
}
}
}
我的屏幕记录: http://www.screenr.com/prx8
推荐答案
您应该调用之前revalidate再重绘此:
You should call revalidate before repaint here:
panel.remove(custompanel);
panel.add(new CustomPanel("/hinhtu2.jpg"), BorderLayout.CENTER);
panel.repaint();
panel.revalidate();
重新验证调用更新容器层次结构,并可能需要重绘后。容器大小调整既不会(重新验证和重绘),这就是为什么在面板出现你调整后的小程序。
Revalidate call updates container hierarchy and after that a repaint might be needed. Container resize does both (revalidate and repaint), thats why the panel appears after you resize the applet.
此外,我在上你的code注意到1坏事:
Also i noticed 1 bad thing in yuor code:
public void paintComponent(Graphics g) {
Image x = Toolkit.getDefaultToolkit().getImage(getClass().getResource(resource));
g.drawImage(x, 0, 0, null);
}
您加载图像的每个时间自定义组件重新绘制。图像越装载进入构造并加载它一次。
You are loading image each time your custom component repaints. Better move the image loading into constructor and load it just once.
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