如何设置和管理 JOptionPane 的布局

Question

我有一个带有一些组件的简单 JOptionPane，我想安排它们。

例如，我想将标签放在文本/密码字段旁边，设置它们的宽度等。

就像我是这样做的，结果当然不是我想要的：

public class CreateApplicationUserScreen {

  CreateApplicationUserScreen(){
    JLabel l_name=new JLabel("Username");
    JLabel l_pass=new JLabel("Password");
    JTextField tf_name=new JTextField(10);
    JPasswordField pf_pass=new JPasswordField(10);
    JButton b_privs = new JButton("Privs");
    JButton b_databases = new JButton("Databases");

    int res = JOptionPane.showOptionDialog(window, 
                                          new Object[] { l_name, tf_name, 
                                                         l_pass, pf_pass, 
                                                         b_privs, b_databases }, 
                                          "Create application user", 
                                          JOptionPane.OK_CANCEL_OPTION,
                                          JOptionPane.PLAIN_MESSAGE,null, 
                                          new String[]{"Create", "Cancel"},
                                          "default");
  }
}

Answer 1

您可以将任何 Swing 组件添加到选项窗格。所以构建你自己的面板：

import java.awt.*;
import javax.swing.*;

public class OptionPanePanel
{
    private static void createAndShowUI()
    {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo( null );
        frame.setVisible( true );

        //  Build a custom panel

        JPanel panel = new JPanel( new GridLayout(2, 2) );
        panel.add( new JLabel("First Name") );
        JTextField firstName = new JTextField(10);
//      firstName.addAncestorListener( new RequestFocusListener(false) );
        panel.add( firstName );
        panel.add( new JLabel("Last Name") );
        JTextField lastName = new JTextField(10);
        panel.add( lastName );

        int result = JOptionPane.showConfirmDialog(
            frame, // use your JFrame here
            panel,
            "Use a Panel",
            JOptionPane.YES_NO_OPTION,
            JOptionPane.PLAIN_MESSAGE);

        if(result == JOptionPane.YES_OPTION)
        {
            System.out.println(firstName.getText() + " : " + lastName.getText());
        }
        else
        {
            System.out.println("Canceled");
        }

        //  Let Option Pane build the panel for you

        Object[] msg = {"First Name:", firstName, "Last Name:", lastName};

        result = JOptionPane.showConfirmDialog(
            frame,
            msg,
            "Use default layout",
            JOptionPane.OK_CANCEL_OPTION,
            JOptionPane.PLAIN_MESSAGE);

        if (result == JOptionPane.YES_OPTION)
        {
            System.out.println(firstName.getText() + " : " + lastName.getText());
        }
        else
        {
            System.out.println("Canceled");
        }
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}

这种方法的一个缺点是焦点会放在按钮上，而不是文本字段上。因此，您可能希望使用 RequestFocusListener 将焦点放在您的第一个文本字段上。

Answer 2

• JOptionPane 使用BoxLayout，在 API 中实现

• 您可以设置任何LayoutManager、Font、Icon等

• 需要调用JOptionPane.pack()，如果改变了LayoutManager

例如

import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.BorderFactory;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;


public class OptionPaneOptions {

    private JPanel options;
    private Object[] items;

    public OptionPaneOptions() {
        options = new JPanel(new GridLayout(0, 3));
        options.add(createOptionPane("Plain Message", JOptionPane.PLAIN_MESSAGE));
        options.add(createOptionPane("Error Message", JOptionPane.ERROR_MESSAGE));
        options.add(createOptionPane("Information Message", JOptionPane.INFORMATION_MESSAGE));
        options.add(createOptionPane("Warning Message", JOptionPane.WARNING_MESSAGE));
        options.add(createOptionPane("Want to do something?", JOptionPane.QUESTION_MESSAGE));
        items = new Object[]{"First", "Second", "Third"};
        JComboBox choiceCombo = new JComboBox(items);
        options.add(titled(new JOptionPane(choiceCombo,
                JOptionPane.QUESTION_MESSAGE, JOptionPane.OK_CANCEL_OPTION), "Question Message"));
        JFrame frame = new JFrame("JOptionPane'Options");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(options, BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);
    }

    static JOptionPane createOptionPane(String message, int type) {
        JOptionPane pane = new JOptionPane(message, type);
        System.out.println(pane.getLayout());
        String title = message;
        if (type == JOptionPane.QUESTION_MESSAGE) {
            title = "Question Message";
            pane.setOptionType(JOptionPane.YES_NO_CANCEL_OPTION);
        }
        return titled(pane, title);
    }

     static <T extends JComponent> T titled(T c, String title) {
        c.setBorder(BorderFactory.createTitledBorder(title));
        return c;
    }

    public static void main(String[] args) {
        OptionPaneOptions test = new OptionPaneOptions();
    }
}