java简单地读写文件

总是忘记java读写文件的代码具体怎么写，写了一个记录如下
String filename="mydict.txt";
File file=new File(filename);
//read file
if(file.exists())
{
try
{
BufferedReader br=new BufferedReader(new FileReader(file));
String temp=null;
while((temp=br.readLine())!=null)
{
System.out.println(temp);

}
}
catch(FileNotFoundException e)
{
System.err.println(e.getMessage());
}
catch(IOException e1)
{
System.err.println(e1.getMessage());

}

}
else
{
System.out.println("file does not exist...");
}

//write file, cover the old content
//write the key sentences
try
{
BufferedWriter bw=new BufferedWriter(new FileWriter(file));
String s="fdjsaifjdisaof";
bw.write(s);
bw.close();
}
catch(IOException e)
{
//.......
}