PrintWriter.write(), FileOutputStream.write writes to the file even when the write permission is removed at the runtime.

Here a file is created a with read, write and execute permissions, and then all the three permissions are removed to avoid unexpected writes by any part of code. But the write methods in PrintWriter, FileOutputStream classes writes to the file without checking the runtime permission changes to the file.

On execution of the following code snippet, the if conditon at Line 1 returns false indicating that file is not writable, but at Line 2 fos.write(2) is able to write into file without throwing any exception.
  
      try {
        File file = new File("fos");
        FileOutputStream fos = new FileOutputStream(file);
        file.setWritable(false,false);
        if (file.canWrite()) // Line 1
            fos.write(1);
        fos.write(2); // Line 2
      }catch(IOException e){
         System.out.println(e);
      }
 Here file.canWrite() returns false ,but fos.write(2) writes to the file without any exception.

File.set{Writable,Executable,Readable}() methods serves its purpose to max , if write methods in java.io recognizes the permissions dynamically.

Please see the following code,version, Result.

<CODE>

import java.io.*;
import static java.lang.System.out;
class Test3 {
    public static void main(String ... args) throws IOException {
      
      
      File f = new File(args[0]);
      
            
      PrintWriter fos = new PrintWriter ( new BufferedWriter(new FileWriter(f)));
      
      out.println("can Read " +f.canRead());
      out.println("can Write " + f.canWrite());
      out.println("can Execute "+ f.canExecute() );
      
      out.println("set Execute false " +f.setExecutable(false,false));
      out.println("set Readable false " + f.setReadable(false,false));
      out.println("set Writable false " + f.setWritable(false,false));
      
      out.println("can Read " +f.canRead());
      out.println("can Write " + f.canWrite());
      out.println("can Execute "+ f.canExecute() );
      
      fos.write("Test Write");
      fos.flush();
      fos.close();
      }
}
</CODE>
<Result>
bash-3.00$ java -version
java version "1.6.0-rc"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-rc-b68)
Java HotSpot(TM) Client VM (build 1.6.0-rc-b68, mixed mode)
bash-3.00$

bash-3.00$ umask
0000
bash-3.00$ ls -l fos
fos: No such file or directory
bash-3.00$ java Test3 fos
can Read true
can Write true
can Execute false
set Execute false true
set Readable false true
set Writable false true
can Read false
can Write false
can Execute false
bash-3.00$ ls -l fos
---------- 1 rg157576 staff 10 Jan 23 2006 fos
bash-3.00$ cat fos
cat: cannot open fos
bash-3.00$ chmod 777 fos
bash-3.00$ cat fos
Test Writebash-3.00$

</Result>