选择文件错误提示

  1 package com.chuangkohua;
  2 
  3 import java.awt.Button;
  4 import java.awt.Dialog;
  5 import java.awt.FlowLayout;
  6 import java.awt.Frame;
  7 import java.awt.Label;
  8 import java.awt.TextArea;
  9 import java.awt.TextField;
 10 import java.awt.event.ActionEvent;
 11 import java.awt.event.ActionListener;
 12 import java.awt.event.KeyAdapter;
 13 import java.awt.event.WindowAdapter;
 14 import java.awt.event.WindowEvent;
 15 import java.io.File;
 16 
 17 public class Test {
 18 
 19     public static void main(String[] args) {
 20         // TODO Auto-generated method stub
 21 
 22         Frame frame = new Frame("小毛炉");
 23         frame.setBounds(300, 100, 600, 500);
 24         TextField field = new TextField(60);
 25         Button button = new Button("转到");
 26         TextArea area = new TextArea(25, 70);
 27         frame.add(field);
 28         frame.add(button);
 29         frame.add(area);
 30         frame.setLayout(new FlowLayout());
 31         frame.setVisible(true);
 32         
 33         frame.addWindowListener(new Demo2());
 34         
 35     /*    button.addActionListener(new ActionListener() {
 36             
 37             @Override
 38             public void actionPerformed(ActionEvent e) {
 39                 // TODO Auto-generated method stub
 40                 String str = field.getText();
 41                 area.setText(str);
 42                 field.setText("");
 43             }
 44         });*/
 45         
 46     
 47         //弹出窗口
 48         Dialog dialog = new Dialog(frame,"提示小窗口",true);
 49         Label label = new Label();
 50         Button button2 = new Button("确定");
 51         dialog.add(label);
 52         dialog.add(button2);
 53         dialog.setBounds(100, 50, 300, 200);
 54         dialog.setLayout(new FlowLayout());
 55         //单击关闭按钮关闭对话框
 56         dialog.addWindowListener(new WindowAdapter() {
 57             public void windowClosing(WindowEvent e){
 58                 dialog.setVisible(false);
 59             }
 60         });
 61         //单击button2按钮关闭对话框
 62         button2.addActionListener(new ActionListener() {
 63             
 64             @Override
 65             public void actionPerformed(ActionEvent e) {
 66                 // TODO Auto-generated method stub
 67                 dialog.setVisible(false);
 68             }
 69         });
 70         
 71         //回车键转到文本区域显示
 72         /*field.addKeyListener(new KeyAdapter() {
 73             public void keyPressed(KeyEvent e){
 74                 if(e.getKeyCode()==KeyEvent.VK_ENTER){
 75                     String filepath = field.getText();
 76                     File dir = new File(filepath);
 77                     if(dir.exists()&&dir.isDirectory()){
 78                         field.setText("");
 79                         String[] name = dir.list();
 80                         for(String names : name){
 81                             area.append(names+"
");
 82                         }
 83                     }
 84                     else{
 85                         String str = "     您输入的信息"+filepath+"有误，请重新输入       ";
 86                         label.setText(str);
 87                         dialog.setVisible(true);
 88                     }
 89                 }
 90             }
 91         });*/
 92         
 93         button.addActionListener(new ActionListener() {
 94             @Override
 95             public void actionPerformed(ActionEvent e) {
 96                 
 97                 // TODO Auto-generated method stub
 98                 String filepath = field.getText();
 99                 File dir = new File(filepath);
100                 if(dir.exists()&&dir.isDirectory()){
101                     field.setText("");
102                     String[] name = dir.list();
103                     for(String names : name){
104                         area.append(names+"
");
105                     }
106                 }
107                 else{
108                     String str = "     您输入的信息"+filepath+"有误，请重新输入       ";
109                     label.setText(str);
110                     dialog.setVisible(true);
111                 }
112             
113             }
114         });
115     }
116 
117 }
118 
119 class Demo2 extends WindowAdapter{
120     public void windowClosing(WindowEvent e){
121         System.exit(0);
122     }
123 }
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原文地址：https://www.cnblogs.com/fujilong/p/4734057.html