awt这块的问题，为何菜单保存点击却保存不进去？ - 黑马程序员技术交流社区

import java.awt.*;
import java.awt.event.*;
import java.io.*;
class AwtDemo3
{
private Frame f;
private TextArea ta;
private FileDialog openDia,saveDia;
private MenuBar mb;
private Menu m,m2,m3,m4;
private MenuItem mi,mi2,mi3,mi4;
AwtDemo3()
{
init();
}
public void init()
{
f = new Frame("AWT");
f.setBounds(200,0,900,600);
mb =new MenuBar();
m =new Menu("文件");
m2 =new Menu("选项");
m3 =new Menu("设置");
m4 =new Menu("工具");
mi =new MenuItem("退出(exit)");
mi2 =new MenuItem("没工具啦");
mi3 =new MenuItem("打开(open)");
mi4 =new MenuItem("保存(save)");
mb.add(m);
mb.add(m2);
mb.add(m3);
m4.add(mi2);
m.add(m4);
m.add(mi3);
m.add(mi4);
m.add(mi);
f.setMenuBar(mb);
openDia =new FileDialog(f,"打开",FileDialog.LOAD);
saveDia =new FileDialog(f,"保存",FileDialog.SAVE);
ta = new TextArea(25,100);
f.add(ta);
myEvent();
f.setVisible(true);
}
public void myEvent()
{
mi4.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
saveDia.setVisible(true);
String dirPath = saveDia.getDirectory();
String fileName = saveDia.getFile();
if(dirPath==null || fileName==null)
return;
ta.setText("");
File file = new File(dirPath,fileName);
try
{
BufferedWriter bw = new BufferedWriter(new FileWriter(file));
bw.write(ta.getText());
bw.flush();
bw.close();
}
catch (IOException b)
{
throw new RuntimeException("写入失败");
}
}
});
mi3.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
openDia.setVisible(true);
String dirPath = openDia.getDirectory();
String fileName = openDia.getFile();
//System.out.println(dirPath+"---"+fileName);
if(dirPath==null || fileName==null)
return;
ta.setText("");
File file = new File(dirPath,fileName);
try
{
BufferedReader br = new BufferedReader(new FileReader(file));
String line = null;
while((line=br.readLine())!=null)
{
ta.append(line+"\r\n");
}
br.close();
}
catch (IOException b)
{
throw new RuntimeException("读取失败");
}
}
});
mi.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
System.exit(0);
}
});
f.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
public void windowOpened(WindowEvent e)
{
System.out.println("启动程序");
}
});
}
public static void main(String[] args)
{
new AwtDemo3();
}
}

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