Ich möchte zählen, dass die Zeilennummer von JTextArea den umgebrochenen Text enthält. Und ich habe den netten Beispielcode vonHier Thread

Aber ich versuche mit Dynamic JTextArea zu modifizieren. Aber die Berechnung der Zeilennummer geht schief.

Hier ist der von mir modifizierte Code:

package fandi.demo;

import java.awt.font.FontRenderContext;
import java.awt.font.LineBreakMeasurer;
import java.text.AttributedCharacterIterator;
import java.text.AttributedString;
import javax.swing.JTextArea;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;

public class JTextAreaCountModified extends javax.swing.JFrame {

    public JTextAreaCountModified() {
        initComponents();
        setLocationRelativeTo(null);

        txtResult.getDocument().addDocumentListener(new DocumentListener() {

            @Override
            public void insertUpdate(DocumentEvent e) {
                if(txtResult.getText().length() > 0) {
                    lblCountLine.setText(String.valueOf(countLines(txtResult)));
                } else {
                    lblCountLine.setText("0");
                }
            }

            @Override
            public void removeUpdate(DocumentEvent e) {
                if(txtResult.getText().length() > 0) {
                    lblCountLine.setText(String.valueOf(countLines(txtResult)));
                }else {
                    lblCountLine.setText("0");
                }
            }

            @Override
            public void changedUpdate(DocumentEvent e) {
                if(txtResult.getText().length() > 0) {
                    lblCountLine.setText(String.valueOf(countLines(txtResult)));
                }else {
                    lblCountLine.setText("0");
                }
            }
        });
    }

    // COUNTING LINE GOES HERE...
    public static int countLines(JTextArea textArea) {
        AttributedString text = new AttributedString(textArea.getText());
        FontRenderContext frc = textArea.getFontMetrics(textArea.getFont()).getFontRenderContext();
        AttributedCharacterIterator charIt = text.getIterator();
        LineBreakMeasurer lineMeasurer = new LineBreakMeasurer(charIt, frc);
        float formatWidth = (float) textArea.getSize().width;
        lineMeasurer.setPosition(charIt.getBeginIndex());

        int noLines = 0;
        while (lineMeasurer.getPosition() < charIt.getEndIndex()) {
            lineMeasurer.nextLayout(formatWidth);
            noLines++;
        }

        int lineEnter = textArea.getLineCount();
        int countLine = noLines + lineEnter;

        return countLine-1;
    } 
    // END OF COUNTING METHOD

    /**
     * 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">//GEN-BEGIN:initComponents
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        jScrollPane1 = new javax.swing.JScrollPane();
        txtResult = new javax.swing.JTextArea();
        jLabel3 = new javax.swing.JLabel();
        lblCountLine = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("JTextArea Line Counting include Wrap");
        setResizable(false);

        jLabel1.setText("Enter paragraph");

        jLabel2.setFont(new java.awt.Font("Tahoma", 1, 11)); // NOI18N
        jLabel2.setForeground(new java.awt.Color(255, 0, 0));
        jLabel2.setText("20 line limit.");

        txtResult.setColumns(20);
        txtResult.setLineWrap(true);
        txtResult.setRows(5);
        txtResult.setWrapStyleWord(true);
        jScrollPane1.setViewportView(txtResult);

        jLabel3.setFont(new java.awt.Font("Tahoma", 1, 11)); // NOI18N
        jLabel3.setText("Information : ");

        lblCountLine.setText("...");

        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()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jLabel3)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(lblCountLine)
                        .addGap(0, 0, Short.MAX_VALUE))
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 458, Short.MAX_VALUE)
                            .addGroup(layout.createSequentialGroup()
                                .addComponent(jLabel1)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(jLabel2)
                                .addGap(0, 0, Short.MAX_VALUE)))
                        .addContainerGap())))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1)
                    .addComponent(jLabel2))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 290, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel3)
                    .addComponent(lblCountLine))
                .addContainerGap(13, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>//GEN-END:initComponents

    /**
     * @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(JTextAreaCountModified.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(JTextAreaCountModified.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(JTextAreaCountModified.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(JTextAreaCountModified.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 JTextAreaCountModified().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify//GEN-BEGIN:variables
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JLabel lblCountLine;
    private javax.swing.JTextArea txtResult;
    // End of variables declaration//GEN-END:variables
}

Bitte helfen Sie, danke :)