Java GUI 编程学习笔记（2）

1 文本框的数据放到文本域显示

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

// -Dfile.encoding=GB18030
public class TextAreaTest {
    public static void main(String[] args) {
        Frame f = new Frame("文本域");
        f.setBounds(400,200,400,300);
        f.setLayout(new FlowLayout());

        TextField tf = new TextField(20);

        Button bu = new Button("数据搬迁");

        TextArea ta = new TextArea(10,40);

        f.add(tf);
        f.add(bu);
        f.add(ta);

        // 窗口关闭
        f.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

        // 按钮添加事件
        bu.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                // 获取文本框的值
                String tf_str = tf.getText().trim();
                // 清空
                tf.setText("");

                //设置文本域
                ta.append(tf_str + "\r\n");

                // 文本框获取光标
                tf.requestFocus();
            }
        });

        f.setVisible(true);
    }
}

2 鼠标移动到按钮上改变背景色

import java.awt.*;
import java.awt.event.*;

public class MouseColor {
    public static void main(String[] args) {
        Frame f = new Frame("鼠标移动改颜色");
        f.setBounds(400, 200, 400, 300);
        f.setLayout(new FlowLayout());

        Button redButton = new Button("Red");

        f.add(redButton);

        // 设置窗体关闭
        f.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

        // 动作监听
        /*redButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                f.setBackground(Color.red);
            }
        });
*/
        //  对按钮添加鼠标监听
        redButton.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseEntered(MouseEvent e) {
                f.setBackground(Color.RED);
            }

            @Override
            public void mouseExited(MouseEvent e) {
                f.setBackground(Color.WHITE);
            }
        });

        f.setVisible(true);
    }
}

3 限制文本框只能输入数字

import java.awt.*;
import java.awt.event.*;

// -Dfile.encoding=GB18030
public class Demo7 {
    public static void main(String[] args) {
        Frame f = new Frame("按钮测试");
        f.setBounds(400, 200, 400, 300);
        //设置流式布局
        f.setLayout(new FlowLayout());

        Label label = new Label("输入 QQ 号码（阿拉伯数字）");
        TextField tf = new TextField(20);

        f.add(label);
        f.add(tf);

        f.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

        // 文本框添加事件
        tf.addKeyListener(new KeyAdapter() {
            @Override
            public void keyPressed(KeyEvent e) {
                char ch = e.getKeyChar();
                if (!(ch >= '0' && ch <= '9')) {
                    e.consume();
                }
            }
        });

        f.setVisible(true);

    }
}