/* * Swing version */import javax.swing.*;import javax.swing.text.*;import javax.swing.event.*;import java.awt.Dimension;import java.awt.BorderLayout;import java.awt.GridBagLayout;import java.awt.GridBagConstraints;import java.awt.event.*;public class DocumentEventDemo extends JApplet                                implements ActionListener {    JTextField textField;    JTextArea textArea;    JTextArea displayArea;    public void init() {        JButton button = new JButton("Clear");        button.addActionListener(this);        textField = new JTextField(20);        textField.addActionListener(new MyTextActionListener());        textField.getDocument().addDocumentListener(new MyDocumentListener());        textField.getDocument().putProperty("name", "Text Field");        textArea = new JTextArea();        textArea.getDocument().addDocumentListener(new MyDocumentListener());        textArea.getDocument().putProperty("name", "Text Area");        JScrollPane scrollPane = new JScrollPane(textArea);        scrollPane.setPreferredSize(new Dimension(200, 75));        displayArea = new JTextArea();        displayArea.setEditable(false);        JScrollPane displayScrollPane = new JScrollPane(displayArea);        displayScrollPane.setPreferredSize(new Dimension(200, 75));        JPanel contentPane = new JPanel();        GridBagLayout gridbag = new GridBagLayout();        GridBagConstraints c = new GridBagConstraints();        contentPane.setLayout(gridbag);        c.gridx = 0;        c.gridy = 0;        c.weightx = 1.0;        c.fill = GridBagConstraints.HORIZONTAL;        gridbag.setConstraints(textField, c);        contentPane.add(textField);        c.gridx = 0;        c.gridy = 1;        c.weightx = 0.0;        c.gridheight = 2;        c.fill = GridBagConstraints.BOTH;        gridbag.setConstraints(scrollPane, c);        contentPane.add(scrollPane);        c.gridx = 1;        c.gridy = 0;        c.weightx = 1.0;        c.weighty = 1.0;        gridbag.setConstraints(displayScrollPane, c);        contentPane.add(displayScrollPane);        c.gridx = 1;        c.gridy = 2;        c.weightx = 0.0;        c.gridheight = 1;        c.weighty = 0.0;        c.fill = GridBagConstraints.HORIZONTAL;        gridbag.setConstraints(button, c);        contentPane.add(button);        setContentPane(contentPane);    }    class MyDocumentListener implements DocumentListener {        final String newline = "\n";        public void insertUpdate(DocumentEvent e) {            updateLog(e, "inserted into");        }        public void removeUpdate(DocumentEvent e) {            updateLog(e, "removed from");        }        public void changedUpdate(DocumentEvent e) {            //Plain text components don't fire these events.        }        public void updateLog(DocumentEvent e, String action) {            Document doc = (Document)e.getDocument();            int changeLength = e.getLength();            displayArea.append(                changeLength + " character"              + ((changeLength == 1) ? " " : "s ")              + action + " " + doc.getProperty("name") + "."              + newline              + "  Text length = " + doc.getLength() + newline);        }    }    class MyTextActionListener implements ActionListener {        /** Handle the text field Return. */        public void actionPerformed(ActionEvent e) {            int selStart = textArea.getSelectionStart();            int selEnd = textArea.getSelectionEnd();            textArea.replaceRange(textField.getText(),                                  selStart, selEnd);            textField.selectAll();        }    }    /** Handle button click. */    public void actionPerformed(ActionEvent e) {        displayArea.setText("");        textField.requestFocus();    }}