Java FilePermission Class

The FilePermission class in Java represents access rights to a file or directory. Accesses are defined by a path name and a set of actions associated with that path. This class is part of the java.io package and extends the Permission class while implementing Serializable.

Example:

FilePermission fp = new FilePermission("GEEKS.txt", "read");

Here, "GEEKS.txt" is the path, and "read" is the action permitted.

Supported Actions:

The FilePermission class supports the following actions:

• read: Grants permission to read the file.
• write: Grants permission to modify/write to the file.
• delete: Grants permission to delete the file using File.delete().
• readlink: Grants permission to read symbolic links.
• execute: Grants permission to execute the file.

Class Declaration of FilePermission Class

public final class FilePermission
  extends Permission
    implements Serializable

Constructor

FilePermission(String path, String actions)

Parameters:

• path: The file or directory path.
• actions: Actions to be allowed (e.g., "read", "write").

Description: Creates a new FilePermission object with the specified actions.

Methods of FilePermission Class

1. equals(Object obj)

Syntax:

public boolean equals(Object obj)

• Description: Checks if the current FilePermission object is equal to the specified object.
• Parameters: obj – the FilePermission object to compare.
• Returns: true if equal, otherwise false.

Example:

import java.io.FilePermission;

public class EqualsExample {
    public static void main(String[] args) {
        FilePermission fp1 = new FilePermission("GEEKS.txt", "read");
        FilePermission fp2 = new FilePermission("GEEKS.txt", "read");

        System.out.println(fp1.equals(fp2)); // Output: true
    }
}

true

2. getActions()

Syntax:

public String getActions()

Returns: Canonical string: representing the actions associated with the object.

Example: 

import java.io.FilePermission;

public class GetActionsExample {
    public static void main(String[] args) {
        FilePermission fp = new FilePermission("GEEKS.txt", "read,write");
        System.out.println(fp.getActions()); // Output: read,write
    }
}

read,write

3. hashCode()

Syntax:

public int hashCode()

Returns: Returns the hash code value for the FilePermission object.

Example: 

import java.io.FilePermission;

public class HashCodeExample {
    public static void main(String[] args) {
        FilePermission fp = new FilePermission("GEEKS.txt", "read");
        System.out.println(fp.hashCode()); // Output: some integer hash value
    }
}

-989797644

4. implies(Permission arg)

Syntax:

public boolean implies(Permission p)

• Description: Determines whether the current FilePermission object implies the specified permission.
• Parameters: p – the permission to check.
• Returns: true if the permission is implied, otherwise false.

Example: 

import java.io.FilePermission;
import java.security.Permission;

public class ImpliesExample {
    public static void main(String[] args) {
        FilePermission fp1 = new FilePermission("GEEKS.txt", "read,write");
        FilePermission fp2 = new FilePermission("GEEKS.txt", "read");

        System.out.println(fp1.implies(fp2)); // Output: true
    }
}

true

5. newPermissionCollection()

Syntax:

public PermissionCollection newPermissionCollection()

• Description: Returns a new PermissionCollection object to hold FilePermission objects.

Example: 

import java.io.FilePermission;
import java.security.PermissionCollection;

public class PermissionCollectionExample {
    public static void main(String[] args) {
        FilePermission fp1 = new FilePermission("GEEKS.txt", "read");
        FilePermission fp2 = new FilePermission("GEEKS.txt", "write");

        PermissionCollection pc = fp1.newPermissionCollection();
        pc.add(fp1);
        pc.add(fp2);

        System.out.println(pc.elements().hasMoreElements()); // Output: true
    }
}

true