Question

我想通过JMenuItem显示行号。但是，显示行号是单独的帧当前未打开的帧，并且单击viewLineNumbers后，create menuitem也无法正常工作。

这是我的代码：

public class LineNumbers extends javax.swing.JFrame {
int i=0;
JTextArea tx,lines;
public LineNumbers() {
    initComponents();
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    scrollPane = new javax.swing.JScrollPane();
    tabbedPane = new javax.swing.JTabbedPane();
    menuBar = new javax.swing.JMenuBar();
    file = new javax.swing.JMenu();
    create = new javax.swing.JMenuItem();
    viewLineNumbers = new javax.swing.JCheckBoxMenuItem();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    scrollPane.setViewportView(tabbedPane);

    file.setText("File");

    create.setText("Create");
    create.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            createActionPerformed(evt);
        }
    });
    file.add(create);

    viewLineNumbers.setSelected(true);
    viewLineNumbers.setText("ViewLineNumbers");
    viewLineNumbers.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            viewLineNumbersActionPerformed(evt);
        }
    });
    file.add(viewLineNumbers);

    menuBar.add(file);

    setJMenuBar(menuBar);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(scrollPane, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 403, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(scrollPane, javax.swing.GroupLayout.DEFAULT_SIZE, 354, Short.MAX_VALUE)
    );

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

private void createActionPerformed(java.awt.event.ActionEvent evt) {                                       
    final JInternalFrame internalFrame = new JInternalFrame("");
    i++;
    internalFrame.setName("Document"+i);
    internalFrame.setClosable(true);
    tx = new JTextArea();
    internalFrame.add(tx, BorderLayout.CENTER);
    tabbedPane.add(internalFrame);
    internalFrame.pack();
    internalFrame.setVisible(true);
}                                      

private void viewLineNumbersActionPerformed(java.awt.event.ActionEvent evt) {                                                
            lines = new JTextArea("");
    lines.setEditable(false);
            lines.setSize(10,10);
    tx.getDocument().addDocumentListener(new DocumentListener(){
        public String getText(){
            int caretPosition = tx.getDocument().getLength();
            Element root = tx.getDocument().getDefaultRootElement();
            String text = "1" + System.getProperty("line.separator");
                            int c=root.getElementIndex( caretPosition );
            for(int i = 2; i < c + 2; i++){
                text += i + System.getProperty("line.separator");
            }
            return text;
        }
        @Override
        public void changedUpdate(DocumentEvent de) {
            lines.setText(getText());
        }
        @Override
        public void insertUpdate(DocumentEvent de) {
            lines.setText(getText());
        }
                    @Override
        public void removeUpdate(DocumentEvent de) {
            lines.setText(getText());
        }
    });
            scrollPane.getViewport().add(tx);
            scrollPane.setRowHeaderView(lines);
}                                               
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(LineNumbers.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(LineNumbers.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(LineNumbers.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(LineNumbers.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new LineNumbers().setVisible(true);
        }
    });
}
// Variables declaration - do not modify                     
private javax.swing.JMenuItem create;
private javax.swing.JMenu file;
private javax.swing.JMenuBar menuBar;
private javax.swing.JScrollPane scrollPane;
private javax.swing.JTabbedPane tabbedPane;
private javax.swing.JCheckBoxMenuItem viewLineNumbers;
// End of variables declaration

}

Answer 1

您需要将文本区域添加到滚动窗格，然后将滚动窗格添加到内部框架。
然后更新上面滚动窗格（包含文本区域）的行标题，而不是包含选项卡式窗格的滚动窗格。

如何使用swing通过menuitem添加行号

1 个答案: