How to set the file permission in Java

In Java, file permissions are very OS specific: *nix , NTFS (windows) and FAT/FAT32, all have different kind of file permissions. Java comes with some generic file permission to deal with it.

Check if the file permission allow :

1. file.canExecute(); – return true, file is executable; false is not.
2. file.canWrite(); – return true, file is writable; false is not.
3. file.canRead(); – return true, file is readable; false is not.

Set the file permission :

1. file.setExecutable(boolean); – true, allow execute operations; false to disallow it.
2. file.setReadable(boolean); – true, allow read operations; false to disallow it.
3. file.setWritable(boolean); – true, allow write operations; false to disallow it.

In *nix system, you may need to configure more specifies about file permission, e.g set a 777 permission for a file or directory, however, Java IO classes do not have ready method for it, but you can use the following dirty workaround :

Runtime.getRuntime().exec("chmod 777 file");

Example:

package com.example.file;

import java.io.File;

import java.io.IOException;

public class FilePermissionExample 

{

    public static void main( String[] args )

    {

    try {

     

     File file = new File("/example/shellscript.sh");

     

     if(file.exists()){

     System.out.println("Is Execute allow : " + file.canExecute());

 System.out.println("Is Write allow : " + file.canWrite());

 System.out.println("Is Read allow : " + file.canRead());

     }

        

     file.setExecutable(false);

     file.setReadable(false);

     file.setWritable(false);

     

     System.out.println("Is Execute allow : " + file.canExecute());

     System.out.println("Is Write allow : " + file.canWrite());

     System.out.println("Is Read allow : " + file.canRead());

     

     if (file.createNewFile()){

       System.out.println("File is created!");

     }else{

       System.out.println("File already exists.");

     }

     

    } catch (IOException e) {

     e.printStackTrace();

   }

    }

}