Applet的工作原理，但Swing组件将不会出现！ [英] Applet works, but swing components won't appear!

问题描述

所以我创建这个小程序，我希望能有充分在它的swing组件。我已经看了所有的文档，我做了小程序，我可以得到的东西在里面显示出来，如果​​我重写更新（图形G）方法，而是简单地添加组件到的contentPane 似乎并没有那样做！我在做什么错了？

So I am creating this applet which I want to have full on swing components in it. I have looked at all the docs, I have made the applet, and I can get something to show up in it if I override the update(Graphics g) method, but simply adding components to the contentPane doesn't seem to be doing it! What am I doing wrong?

import javax.swing.JApplet;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;

import org.steephill.kindlab.LabApp;

import com.jgoodies.forms.layout.CellConstraints;
import com.jgoodies.forms.layout.FormLayout;

public class ClientApplet extends JApplet {

    ClientTreePanel treePanel;

    public void destroy() {
    	// Put your code here
    }

    public String getAppletInfo() {
    	return "KindLab Client Applet";
    }

    public void init() {

    	try {
    		LabApp.initializeHibernate();
    		if (!LabApp.authenticate("user", "pass")) {

    			JOptionPane.showMessageDialog(this, "authentication failed");
    		} else {

    			try {
    		        javax.swing.SwingUtilities.invokeAndWait(new Runnable() {
    		            public void run() {
    		                createGUI();
    		            }
    		        });
    		    } catch (Exception e) {
    		        System.err.println("createGUI didn't successfully complete");
    		    }

    				}
    	} catch (Exception ex) {
    		JOptionPane.showMessageDialog(this, "error intitializing applet\r\n" + ex.getMessage());
    	}
    }

    protected void createGUI() {

    	treePanel = new ClientTreePanel();
    	treePanel.setVisible(true);
    	getContentPane().add(new JLabel("TESTING!"));
    	getContentPane().add(treePanel);

    	System.out.println("THIS DOES RUN");
    }

    public void start() {
    	// Put your code here
    }

    public void stop() {
    	// Put your code here
    }

    /*  if I uncomment this method, it WORKS and I get "Hello World!"
    public void paint(Graphics g) {
    	super.paint(g);
    	g.drawString("Hello World!",25,25);
    }
     */
}

请，帮帮忙！谢谢你！
约书亚

Please, help! And thank you! Joshua

推荐答案

我看到几个问题你code位置：

I see several problems with your code here:

1. 您不要叫你的GUI安装结束包（）


2. 您添加几个组件到ap​​plet的内容窗格中，但没有任何布局约束。默认的内容窗格通常是一个BorderLayout的，所以增加了两个部件不受任何约束，很可能只会把ClientTreePanel之上。

既然你不叫包（），布局将不被计算出来，这对于你的情况可能会导致没有显示（你没有提供的code代表ClientTreePanel）。

Since you do not call pack(), the layout will not be calculated, which for your case probably results in nothing being displayed (you did not provide the code for ClientTreePanel).

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