[javaSE] GUI（练习-列出指定目录内容）详解编程语言

import java.awt.Button; 
import java.awt.FlowLayout; 
import java.awt.Frame; 
import java.awt.TextArea; 
import java.awt.TextField; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.event.WindowAdapter; 
import java.awt.event.WindowEvent; 
import java.io.File; 
 
public class FrameDemo { 
    private Frame frame; 
    private TextField tf; 
    private TextArea ta; 
    private Button button; 
 
    public FrameDemo() { 
        init(); 
    } 
 
    /** 
     * 初始化 
     */ 
    public void init() { 
        frame = new Frame("测试窗体"); 
        frame.setBounds(300, 200, 300, 400); 
        frame.setLayout(new FlowLayout()); 
 
        tf = new TextField(20); 
        button = new Button("转到"); 
        ta = new TextArea(30, 30); 
        frame.add(button); 
        frame.add(tf); 
        frame.add(ta); 
        frame.setVisible(true); 
 
        addEventAction(); 
    } 
 
    /** 
     * 添加事件 
     */ 
    public void addEventAction() { 
        // 退出 
        frame.addWindowListener(new WindowAdapter() { 
            @Override 
            public void windowClosing(WindowEvent e) { 
                System.exit(0); 
            } 
        }); 
        // action事件 
        button.addActionListener(new ActionListener() { 
            @Override 
            public void actionPerformed(ActionEvent e) { 
                String dirName = tf.getText(); 
                File file = new File(dirName); 
 
                if (!file.isDirectory() || !file.exists()) { 
                    ta.setText("目录不存在"); 
                    return; 
                } 
 
                String[] files = file.list(); 
                StringBuilder sb = new StringBuilder(); 
                for (String name : files) { 
                    sb.append(name); 
                    sb.append("/r/n"); 
                } 
                ta.setText(sb.toString()); 
            } 
        }); 
    } 
 
    /** 
     * @param args 
     */ 
    public static void main(String[] args) { 
        new FrameDemo(); 
    } 
 
}