Mark File or Directory as Read-Only in Java

A file can be set to read-only by using the method java.io.File.setReadOnly(). This method requires no parameters and it returns true if the file is set to read-only and false otherwise. The method java.io.File.canWrite() is used to check whether the file can be written to in Java and if not, then the file is confirmed to be read-only.

A program that demonstrates this is given as follows −

Example

 Live Demo

import java.io.File;
public class Demo {
   public static void main(String[] args) {
      boolean flag;
      try {
         File file = new File("demo1.txt");
         file.createNewFile();
         flag = file.setReadOnly();
         System.out.println("File is read-only?: " + flag);
         flag = file.canWrite();
         System.out.print("File is writable?: " + flag);
      } catch(Exception e) {
         e.printStackTrace();
      }
   }
}

The output of the above program is as follows −

Output

File is read-only?: true
File is writable?: false

Now let us understand the above program.

The file can be set to read-only by using the method java.io.File.setReadOnly() and its return value is printed. The method java.io.File.canWrite() is used to is confirm that the file is read-only and to do that, its return value is printed. A code snippet that demonstrates this is given as follows −

try {
   File file = new File("demo1.txt");
   file.createNewFile();
   flag = file.setReadOnly();
   System.out.println("File is read-only?: " + flag);
   flag = file.canWrite();
   System.out.print("File is writable?: " + flag);
} catch(Exception e) {
   e.printStackTrace();
}