java Java问题如何刷新面板
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Java issue How to refresh a panel
提问by Timothy Montanez
Hey guys I'm a huge noob at Java xD, got sorta of a issue, basically I have a JMenu and when a person clicks on a JMenuItem I want the middle panel to refresh and display some new stuff. So I tried the .removeAll which works fine but when I try to add something it wont show.
嘿伙计们，我是 Java xD 的一个大菜鸟，遇到了一个问题，基本上我有一个 JMenu，当有人单击 JMenuItem 时，我希望中间面板刷新并显示一些新内容。所以我尝试了 .removeAll ，它工作正常，但是当我尝试添加一些东西时它不会显示。
Note: I'm using the WindowBuilder PRO, so I still trying to get use to it and whatnot
注意：我使用的是 WindowBuilder PRO，所以我仍在尝试使用它等等
Here's my code :]
这是我的代码:]
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JMenu;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SpringLayout;
import java.awt.List;
import javax.swing.JLabel;
import javax.swing.JTextPane;
import javax.swing.JSeparator;
import org.eclipse.wb.swing.FocusTraversalOnArray;
import java.awt.Component;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.Panel;
import java.awt.GridBagConstraints;
public class HomeScreen {
JFrame frame;
private final Panel panel = new Panel();
public HomeScreen(String name) {
initialize(name);
}
/**
* Initialize the contents of the frame.
*/
private void initialize(String name) {
frame = new JFrame("Timzys CMS / Monitor / Account( " + name + " )");
frame.setResizable(false);
frame.setSize(694,525);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JMenuBar menuBar = new JMenuBar();
frame.setJMenuBar(menuBar);
JMenu mnMonitor = new JMenu("Monitor");
menuBar.add(mnMonitor);
JMenuItem mntmUsers = new JMenuItem("Users");
mnMonitor.add(mntmUsers);
JMenuItem mntmContentPosts = new JMenuItem("Content Posts");
mnMonitor.add(mntmContentPosts);
JMenuItem mntmLogs = new JMenuItem("Logs");
mnMonitor.add(mntmLogs);
JMenu mnExtras = new JMenu("Extras");
menuBar.add(mnExtras);
mntmUsers.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
frame.getContentPane().removeAll();
frame.getContentPane().add(new JLabel("Test"));
frame.getContentPane().revalidate();
}
});
JMenuItem mntmFeedbacksuggestions = new JMenuItem("Feedback/Suggestions");
mnExtras.add(mntmFeedbacksuggestions);
frame.getContentPane().setLayout(null);
panel.setBounds(0, 0, 688, 476);
frame.getContentPane().add(panel);
panel.setLayout(null);
JTextPane txtpnWelcomeTimzysCms = new JTextPane();
txtpnWelcomeTimzysCms.setFont(new Font("Arial", Font.PLAIN, 18));
txtpnWelcomeTimzysCms.setEditable(false);
txtpnWelcomeTimzysCms.setText("Welcome Timzys CMS Monitor. If you are here then you are a admin! So please do not tamper with any important things. If you have questions or suggestions goto the extras tab and submit a feedback idea. Enjoy!");
txtpnWelcomeTimzysCms.setBounds(10, 11, 668, 72);
panel.add(txtpnWelcomeTimzysCms);
}
}
采纳答案by Reimeus
The problem is that because you have set the frame's layout to null, the new JLabelthat you add will need to have its size set. e.g.:
问题是因为您已将框架的布局设置为空，所以JLabel您添加的新元素需要设置其大小。例如：
JLabel label = new JLabel("Test");
label.setSize(100, 100);
frame.getContentPane().add(label);
As an aside:Actually I wonder why you are mixing AWT & Swing components here. You have a heavyweight AWT panel added to the frame which blocks out the menus. Switching to JPanelwould fix this.
顺便说一句：实际上我想知道您为什么在这里混合 AWT 和 Swing 组件。您有一个重量级的 AWT 面板添加到框架中，它挡住了菜单。切换到JPanel将解决此问题。
回答by Peter Butkovic
Probably you're facing similar problem as someone else in the question:
Java Swing revalidate() vs repaint()
可能您正面临与问题中的其他人类似的问题：
Java Swing revalidate() vs repaint()
As suggested: try to call repaintinstead of revalidate(the one you're calling right now in your implementation of method actionPerformed)
按照建议：尝试调用repaint而不是revalidate（您现在在方法实现中调用的那个actionPerformed）
