java - 将窗口添加到容器错误

Question

我正在尝试创建一个 Java swing 应用程序，单击按钮即可显示一个表格。我收到“向容器添加窗口”错误。我知道我可能应该尝试添加 JPanel 而不是 JFrame，但我的努力不起作用。任何帮助，将不胜感激。下面是代码。

import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author Courtney
 * javax.swing.JFrame
 */
public class TablePractice extends javax.swing.JFrame {

    /**
     * Creates new form TablePractice
     */
    public TablePractice() {
        initComponents();
        String[] columnNames = {"First Name",
                                "Last Name",
                                "Sport",
                                "# of Years",
                                "Vegetarian"};

        Object[][] data = {
        {"Kathy", "Smith",
         "Snowboarding", new Integer(5), new Boolean(false)},
        {"John", "Doe",
         "Rowing", new Integer(3), new Boolean(true)},
        {"Sue", "Black",
         "Knitting", new Integer(2), new Boolean(false)},
        {"Jane", "White",
         "Speed reading", new Integer(20), new Boolean(true)},
        {"Joe", "Brown",
         "Pool", new Integer(10), new Boolean(false)}
        };

        final JTable table = new JTable(data, columnNames);
        table.setPreferredScrollableViewportSize(new Dimension(500, 70));
        table.setFillsViewportHeight(true);

        //Create the scroll pane and add the table to it.
        JScrollPane scrollPane = new JScrollPane(table);

        //Add the scroll pane to this panel.
        add(scrollPane);
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jButton1 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jButton1.setText("Get Table");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jButton1)
                .addContainerGap(311, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(19, 19, 19)
                .addComponent(jButton1)
                .addContainerGap(258, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                        

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         


         //Create and set up the window.
        //JPanel panel = new JPanel();
        JFrame frame = new JFrame("TablePractice");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create and set up the content pane.
        TablePractice newContentPane = new TablePractice();
        //newContentPane.setOpaque(true); //content panes must be opaque
        frame.getContentPane().add(newContentPane);
        //frame.setContentPane(newContentPane);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }                                        

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(TablePractice.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(TablePractice.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(TablePractice.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(TablePractice.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new TablePractice().setVisible(true);


            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    // End of variables declaration                   
}

Answer 1

TablePractice 扩展自 JFrame (这是一种窗口类型)，但您尝试将其添加到 frame 这是一个JFrame(这也是一种窗口类型)。

允许一个窗口包含在另一个窗口中是没有意义的。

这就是为什么不建议直接从 JFrame 等顶级容器扩展的原因之一，而是使用 JPanel 并将组件添加到任何实例您需要的窗口(或其他容器)

您可能还想看看 The Use of Multiple JFrames, Good/Bad Practice?

另一种想法是，当您想要更改表显示的数据时，只需更改表的模型即可