textdemo.java

java应用开发详解

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

public class TextDemo extends JApplet implements ActionListener 
{
    JTextField textField;
    JTextArea textArea;
    String newline = "\n";

    public TextDemo() 
    {
        getRootPane().putClientProperty("defeatSystemEventQueueCheck",
                                        Boolean.TRUE);
    }

    public void init() 
    {
        //实例化文本域与文本框
        textField = new JTextField(20);
        textField.addActionListener(this);

        textArea = new JTextArea(5, 20);
        textArea.setEditable(false);
        JScrollPane scrollPane = new JScrollPane(textArea,
                                       JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
                                       JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);

        //使用网格组布局管理器添加组件
        GridBagLayout gridBag = new GridBagLayout();
        Container contentPane = getContentPane();
        contentPane.setLayout(gridBag);
        GridBagConstraints c = new GridBagConstraints();
        c.gridwidth = GridBagConstraints.REMAINDER;

        c.fill = GridBagConstraints.HORIZONTAL;
        gridBag.setConstraints(textField, c);
        contentPane.add(textField);

        c.fill = GridBagConstraints.BOTH;
        c.weightx = 1.0;
        c.weighty = 1.0;
        gridBag.setConstraints(scrollPane, c);
        contentPane.add(scrollPane);
    }

    //执行相应的事件
    public void actionPerformed(ActionEvent evt) 
    {
        String text = textField.getText();
        textArea.append(text + newline);
        textField.selectAll();
    }
}