Java Swing JComboBox 不可编辑

Question

我遇到了一个非常奇怪的问题。我有一个包含 JTextFields 和 JComboBoxes 的 JPanel。我可以在加载 JPanel 时更改 JComboBox，但是只要我触摸或编辑其中一个 JTextFields，它就不允许我更改任何组合框...

这是一个有效的 MCVE。您可以立即使用它，您会看到错误。

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Panel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Properties;

import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;


public class Main extends JFrame{

    private static JTextField s;
    private static JTabbedPane tabbedPane;
    private static JPanel config;
    private static JComboBox<Object> dns;
    private static JComboBox<Object> dnsmm;
    private static JButton save;
    private static String interval;
    private static String dnsen;
    private static String dnsm;
    private static JPanel server;
    static JPanel contentPane;

    public static void main(String[] args) throws InterruptedException {

            EventQueue.invokeLater(new Runnable() {
                public void run() {
                    try {
                        Main frame = new Main();
                        frame.setVisible(true);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            });
    }


    public Main() throws IOException {

        setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 655, 470);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(1, 1));
        setContentPane(contentPane);

        tabbedPane = new JTabbedPane(JTabbedPane.TOP);
        contentPane.add(tabbedPane, BorderLayout.CENTER);

        setResizable(false);

        server = new JPanel();
        server.setLayout(new BorderLayout(0, 0));

        ServerPanel();
    }

    public static void ServerPanel() throws IOException{ 

        tabbedPane.addTab("Manage Server", server);
        InputStream in = new FileInputStream("config.dedserver");
        Properties p = new Properties();
        p.load(in);
        in.close();
        String saveInt = p.getProperty("saveInterval");
        String dnse = p.getProperty("enableDns");
        String dnsmo = p.getProperty("serverMode");

        config = new JPanel();
        server.add(config, BorderLayout.CENTER);    
        config.setLayout(new BoxLayout(config, BoxLayout.PAGE_AXIS));


        //saveint
        Panel panel_6 = new Panel();
        config.add(panel_6);
        JLabel sl = new JLabel("Save Interval (milliseconds):    ");
        panel_6.add(sl);
        s = new JTextField(saveInt);
        panel_6.add(s);
        s.setColumns(10);

        //dnsenabled
        Panel panel_9 = new Panel();
        config.add(panel_9);
        JLabel dnsl = new JLabel("DNS Enabled:    ");
        panel_9.add(dnsl);
        String[] dnsS = { "true", "false" };
        dns = new JComboBox<Object>(dnsS);
        dns.setSelectedItem(dnse);
        dns.addActionListener(dns);
        panel_9.add(dns);


        //dnsmode
        Panel panel_10 = new Panel();
        config.add(panel_10);
        JLabel dnsml = new JLabel("DNS Server Mode:    ");
        panel_10.add(dnsml);
        String[] dnsm = { "local", "remote" };
        dnsmm = new JComboBox<Object>(dnsm);
        dnsmm.setSelectedItem(dnsmo);
        dnsmm.addActionListener(dnsmm);
        panel_10.add(dnsmm);

        JPanel panel_7= new JPanel();
        config.add(panel_7);
        save = new JButton("Save");
        panel_7.add(save);
        save.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                errorCheck();       
            }
        });
    }

    public static void errorCheck(){
        interval = s.getText();
        dnsen = (String) dns.getSelectedItem();
        dnsm = (String) dnsmm.getSelectedItem();

        interval = checkValues(interval, "60000", "save interval");
        saveValues();
    }

    public static String checkValues(String value, String def, String name){
        String val;
        try{
            Long.parseLong(value);
            val = ""+value+"";
        }catch(NumberFormatException e){
            JOptionPane.showMessageDialog(null, "You did not enter a valid number for the "+ name + " field! It has been set to the default.");
            val = def;
        }
        return val;
    }

    public static void saveValues(){
        try {
                Properties props = new Properties();
                props.setProperty("saveInterval", interval);
                props.setProperty("serverMode", dnsm);
                props.setProperty("enableDns", dnsen);

                File f = new File("config.dedserver");
                OutputStream out = new FileOutputStream(f);
                props.store(out, "");

            JOptionPane.showMessageDialog(null, "Saved Config Values!");

            }
            catch (Exception e ) {
                e.printStackTrace();
                }

        }
}

要使其正常工作，您还需要在项目的根目录中创建一个 config.dedserver 并将以下内容添加到其中:

#
#Thu Jul 09 08:29:33 BST 2015
saveMethod=h2
startingGems=9999999999
enableDns=true
startingGold=9999999999
startingDarkElixir=9999999999
startingElixir=9999999999
serverMode=remote
saveInterval=30000
maxNameChanges=100

完整的 ServerPanel.java 代码位于:http://pastebin.com/tvBENHQa

我不确定为什么这不起作用。有人有什么想法吗？

谢谢!

Answer 1

将 Panel 替换为 JPanel 您将 awt Component 与导致问题的 Swing 混合在一起。

Swing components are "lightweight" (rendered by Java) while AWT components are "heavyweight" (implemented as components in the host platform) - this means you will have problems if you put AWT components inside Swing components (the other way round is fine)

//saveint
   // Panel panel_6 = new Panel();// replace as below
    JPanel panel_6 = new JPanel();

//dnsenabled
   // Panel panel_9 = new Panel();
   JPanel panel_9 = new JPanel();

//dnsmode
    //Panel panel_10 = new Panel();
    JPanel panel_10 = new JPanel();

并且还删除了@KDM 所说的 Action 监听器