Data hiding in java

In java it is achieved by using a keyword 'private' keyword and the process is called data hiding. It is used as security such that no internal data will be accessed without authentication. An unauthorized end user will not get access to internal data.

v   Access Specifier

1. Public
2. Private
3. Protected
4. Default

 

 

Access From	Public	default	private
In the Class
In the same package
In another Package

 1. Public :

-        Public member access with in the class with in the same package and with in another package.

-        Example:

     When methods, variables, classes, and so on are declared public, then we can access them from anywhere. The public access modifier has no scope restriction. For example,

// Animal.java file

// public class

public class Animal {

    // public variable

    public int legCount;

    // public method

    public void display() {

        System.out.println("I am an animal.");

        System.out.println("I have " + legCount + " legs.");

    }

}

// Main.java

public class Main {

    public static void main( String[] args ) {

        // accessing the public class

        Animal animal = new Animal();

        // accessing the public variable

        animal.legCount = 4;

        // accessing the public method

        animal.display();

    }

}

 

Output:

I am an animal.

I have 4 legs.

 2.  Private :

-        Private member only access in class.

Example:

class Data {

    // private variable

    private String name;

}

public class Main {

    public static void main(String[] main){

        // create an object of Data

        Data d = new Data();

        // access private variable and field from another class

        d.name = "Tech Ocean";

    }

}

 

Output:

Main.java:18: error: name has private access in Data

        d.name = "Tech Ocean";

 -> The error is generated because we are trying to access the private variable of the Data class from the Main class.

->  You might be wondering what if we need to access those private variables. In this case, we can use the getters and setters method. For example,

 

class Data {

    private String name;

    // getter method

    public String getName() {

        return this.name;

    }

    // setter method

    public void setName(String name) {

        this.name= name;

    }

}

public class Main {

    public static void main(String[] main){

        Data d = new Data();

        // access the private variable using the getter and setter

        d.setName("Tech Ocean");

        System.out.println(d.getName());

    }

}

 

Output:

Tech Ocean

 

 3.  Protected :

-        Protected member access from derived/child  class .

-        When methods and data members are declared protected, we can access them within the same package as well as from subclasses. For example,

class Animal {

    // protected method

    protected void display() {

        System.out.println("I am an animal");

    }

}

class Dog extends Animal {

    public static void main(String[] args) {

        // create an object of Dog class

        Dog dog = new Dog();

         // access protected method

        dog.display();

    }

}

 

Output:

I am an animal

 4.     Default :

-        Default member access from same class and in the same package.

Example:

class Data {

    // default variable

    String name;

}

public class Main {

    public static void main(String[] main){

        // create an object of Data

        Data d = new Data();

        // access default variable and field from another class

        d.name = "Tech Ocean";

        System.out.println(d.name());

    }

}

 

Output:

Tech Ocean