Java Program to Make a File Read-Only

A read-only file is a file that can be opened and read but cannot normally be modified. Java provides methods in the File class to change the writable status of a file.

• The setReadOnly()method marks a file as read-only and returns a boolean value indicating whether the operation was successful.
• The setWritable(false) method can also be used to disable write access to a file.
• The canWrite() method can be used to check whether the file is currently writable.

Examples

Input: file = "GFG.java"
Output: Is File is read-only? : true
Output: Is File is writable? : false

Input: file = "test.txt"
Output: Is File read-only? : true
Output: Is File writable? : false

Methods to Make a File Read-Only

Java provides methods such as setReadOnly() and setWritable(false) to disable write access to a file and verify its writable status.

1.setReadOnly()

The setReadOnly() method of the File class is used to make a file read-only. It does not require any parameter and returns a boolean value. If the method returns true, the file was successfully marked as read-only. If it returns false, the operation was not successful.

Syntax

file.setReadOnly();

Approach

1. Create an object of the File class with the file path.
2. Create the file if it does not already exist.
3. Call the setReadOnly() method.
4. Store the returned boolean value.
5. Use canWrite() to verify whether the file is writable.

import java.io.File;

public class GFG {

    public static void main(String[] args)
    {
        // flag variable which contains the boolean
        // value returned by setReadOnly() function
        boolean flag;

        try {

            File file = new File("GFG.java");

            // creates a new file
            file.createNewFile();

            // flag the file to be read-only
            flag = file.setReadOnly();

            System.out.println("Is File is read-only ? : "
                               + flag);

            // checking whether Is file  writable
            flag = file.canWrite();
            System.out.println("Is File is writable ? : "
                               + flag);
        }

        catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Output: 

Explanation: The program creates a file and uses setReadOnly() to disable write access. The canWrite() method then returns false, indicating that the file is read-only.

Method 2: Using setWritable() Method

The setWritable() method can be used to control whether a file is writable. By passing false as the argument, write access to the file is disabled, making it read-only.

Syntax

file.setWritable(false);

Approach

1. Create a File object with the path of the file.
2. Call setWritable(false) to disable write access.
3. Use canWrite() to check whether the file is writable.
4. Display the appropriate message based on the result.

import java.io.File;

public class ChangetoReadOnly {

    public static void main(String[] args) {

        File file = new File("test.txt");

        try {
            // Create the file if it does not exist
            file.createNewFile();

            // Make the file read-only
            boolean result = file.setReadOnly();

            System.out.println("Is File read-only? : " + result);

            // Check whether the file is writable
            System.out.println("Is File writable? : " + file.canWrite());
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Output:

Explanation: setWritable(false) attempts to disable write access to the specified file. The canWrite() method is then used to check whether the file is currently writable.