Java.io.FilePermission Class in Java

java.io.FilePermission class is used to represent access to a file or a directory. These accesses are in the form of a path name and a set of actions associated to the path name(specifies which file to be open along with  the extension and the path). For Example, in FilePermission(“GEEKS.txt”, “read”) “GEEKS.txt” is the path and “read” is action being performed. These actions are as follows :

• read : read permission to the file
• write : write permission to the file
• delete : delete permission to the file by calling File.delete
• readlink : read link permission
• execute : executed the permission

Declaration : 

public final class FilePermission
   extends Permission
      implements Serializable

Constructors : 

FilePermission(String p, String a) : Creates a new file permission object with "a" action.

Methods of FilePermission Class : 

• equals(Object FP_obj) : java.io.FilePermission.equals(Object FP_obj) tells whether the two (i.e. checks the FP_obj pathname and filename with this object) FilePermission objects are equal or not. 
• Syntax :

public boolean equals(Object FP_obj)
Parameters : 
FP_obj : the FilePermission object to be verified with this object
Returns :
true : if both the objects are equal else, false.
Exception : 
----------

• Implementation : 

Java

// Java Program illustrating equals() method

import java.io.*;
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        boolean bool = false;

        // Creating new FilePermissions("Path", "action")
        FilePermission FP_obj1 = new FilePermission("GEEKS", "read");
        FilePermission FP_obj2 = new FilePermission("ABC", "write");
        FilePermission FP_obj3 = new FilePermission("GEEKS", "read");

        // Use of equals method
        bool = FP_obj2.equals(FP_obj1);
        System.out.println("Whether FP_obj1 equals FP_obj2 : " + bool);

        bool = FP_obj2.equals(FP_obj3);
        System.out.println("Whether FP_obj2 equals FP_obj2 : " + bool);

        bool = FP_obj1.equals(FP_obj3);
        System.out.println("Whether FP_obj3 equals FP_obj1 : " + bool);


    }
}

• Output : 

Whether FP_obj1 equals FP_obj2 : false
Whether FP_obj2 equals FP_obj2 : false
Whether FP_obj3 equals FP_obj1 : true

• getActions() : java.io.FilePermission.getActions() tells the action of this FilePermission Object. If in case there are two actions along with the object : delete and read, then the method will return “read, delete”. In such cases this method returns “canonical string” : read, write, execute, delete, readlink
• Syntax :

public String getActions()
Parameters : 
----------
Returns :
canonical string : representing the actions associated with the object.
Exception : 
----------

• Implementation :

Java

// Java Program illustrating getActions() method
import java.io.*;
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // Creating new FilePermissions
        FilePermission FP_obj1 = new FilePermission("GEEKS", "read, delete, write");
        FilePermission FP_obj2 = new FilePermission("ABC", "write, read, execute");
        FilePermission FP_obj3 = new FilePermission("GEEKS", "delete, readlink, read");

        // Use of getActions() method
        String str = FP_obj1.getActions();
        System.out.println("Actions with FP_obj1 : " + str);

        str = FP_obj2.getActions();
        System.out.println("Actions with FP_obj2 : " + str);

        str = FP_obj3.getActions();
        System.out.println("Actions with FP_obj3 : " + str);

    }
}

• Output : 

Actions with FP_obj1 : read,write,delete
Actions with FP_obj2 : read,write,execute
Actions with FP_obj3 : read,delete,readlink

• hashCode() : java.io.FilePermission.hashCode() returns hash code for the argumented FilePermission Object 
• Syntax :

public int hashCode()
Parameters : 
--------
Returns :
hash code value for the argumented object
Exception : 
----------

• Implementation : 

Java

// Java Program illustrating hashCode() method

import java.io.*;
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // Creating new FilePermissions
        FilePermission FP_obj1=new FilePermission("GEEKS", "read, delete, write");

        // Use of hashCode() method

        int i = FP_obj1.hashCode();
        System.out.println("hashCode value for FP_obj1 : " + i);

    }
}

• Output : 

hashCode value for FP_obj1 : 0

• implies(Permission arg) :java.io.FilePermission.implies(Permission arg) tells whether this FilePermision has the argumented Permission or not. Syntax :

public boolean implies(Permission arg)
Parameters : 
arg : Permission to be checked 
Returns :
true if the FilePermission object has the argumented Permission else, false
Exception : 
----------

• Implementation :

Java

// Java Program illustrating implies() method

import java.io.*;
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // Creating new FilePermissions
        FilePermission FP_obj1 = new FilePermission("GEEKS", "read");
        FilePermission FP_obj2 = new FilePermission("ABC", "write");
        FilePermission FP_obj3 = new FilePermission("GEEKS", "delete");

        // Use of implies() method

        boolean check = FP_obj1.implies(FP_obj2);
        System.out.println("Using implies() for FP_obj1 : " + check);


        // Checked here with the same FilePermission object
        check = FP_obj2.implies(FP_obj2);
        System.out.println("Using implies() for FP_obj2 : " + check);

    }
}

• Output : 

Using implies() for FP_obj1 : false
Using implies() for FP_obj2 : true

• newPermissionCollection() :java.io.FilePermission.newPermissionCollection() creates PermissionCollection object having the FilePermission objects. Syntax :

public PermissionCollection newPermissionCollection()
Parameters : 
arg : Permission to be checked 
Returns :
new PermissionCollection object having the FilePermission objects.
Exception : 
----------

• Implementation :

Java

// Java Program illustrating newPermissionCollection() method

import java.io.*;
import java.security.PermissionCollection;
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // Creating new FilePermissions
        FilePermission FP_obj1 = new FilePermission("GEEKS.txt", "read");

        // Creating new PermissionCollection
        // Use of newPermissionCollection()
        PermissionCollection FP = FP_obj1.newPermissionCollection();

        // Collecting the Permissions of FP_obj1 for FP
        FP.add(FP_obj1);

        boolean check = FP.implies(new FilePermission("GEEKS.txt", "read"));
        System.out.println("Is newPermissionCollection() working : " + check);

    }
}

• Output : 

Is newPermissionCollection() working : true

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