一个括号引发的血案 - 黑马程序员技术交流社区

import java.awt.*;
import java.awt.event.*;
import java.io.*;
class MyMenuDemo
{
private Frame f;
private Menu fileMenu,subMenu;
private MenuBar mbar;
private Button btn;
private MenuItem openItem,saveItem,closeItem;
private TextArea ta;
private FileDialog dia,saveDia;
private File file;
MyMenuDemo()
{
init();
}
public void init()
{
f =new Frame("MyMenuDemo");
f.setBounds(300,200,500,400);
// f.setLayout(new FlowLayout());流式布局，默认的话是边界布局
mbar =new MenuBar();
fileMenu =new Menu("文件");
//subMenu =new Menu("子菜单");//声明子类new父类是不可以的：subMenu=new MenuItem();
saveItem =new MenuItem("保存");//声明父类new子类是可以的:subItem =new Menu();
//subMenu.add(subItem);
openItem =new MenuItem("打开");
closeItem =new MenuItem("关闭");
fileMenu.add(openItem);
fileMenu.add(saveItem);
fileMenu.add(closeItem);
mbar.add(fileMenu);
f.setMenuBar(mbar);
ta =new TextArea();
f.add(ta);
dia =new FileDialog(f,"打开文件-test",FileDialog.LOAD);
saveDia =new FileDialog(f,"保存文件-test",FileDialog.SAVE);
myEvent();
f.setVisible(true);
}
public void myEvent()
{
f.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
closeItem.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
System.exit(0);
}
});
openItem.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
dia.setVisible(true);
String fileDir =dia.getDirectory();
String fileName =dia.getFile();
//System.out.println(fileDir+""+fileName);
if (fileDir==null || fileName==null)
{
return ;
}
ta.setText("");
file =new File(fileDir,fileName);
sop((file==null)==(fileDir==null || fileName==null));
BufferedReader bufr =null;
try
{
bufr =new BufferedReader(new FileReader(file));
String line=null;
while((line=bufr.readLine())!=null)
{
ta.append(line+"\r\n");
}
}
catch (IOException ex)
{
throw new RuntimeException("读取失败");
}
finally
{
try
{
if (bufr!=null)
{
bufr.close();
}
}
catch (IOException ee)
{
throw new RuntimeException("关闭文件失败");
}
}
}
});
saveItem.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if (file==null)
{
saveDia.setVisible(true);
String filePath=saveDia.getDirectory();
String fileName=saveDia.getFile();
if (filePath ==null || fileName==null)
return ;
file =new File(filePath,fileName);
} //一个括号引发的学案
try
{
BufferedWriter bufw =new BufferedWriter(new FileWriter(file));
String text=ta.getText();
//sop(text+"111");
bufw.write(text);
bufw.close();
}
catch (IOException ee)
{
throw new RuntimeException("保存失败");
}
}
});
}
public static void main(String[] args)
{
new MyMenuDemo();
File f =new File("D:\\","copy.txt");
String filePath=f.getParent();
String fileName=f.getName();
sop(f);
sop((f==null)==(filePath==null || fileName==null));
}
public static void sop(Object obj)
{
System.out.println(obj);
}
}

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