Encapsulation in JAVA

Encapsulation:

Encapsulation in Java or object oriented programming language is a concept which enforce protecting variables, functions from outside of class, in order to better manage that piece of code and having least impact or no impact on other parts of program due to change in protected code.

Encapsulation is the technique of making the fields in a class private and providing access to the fields via public methods. If a field is declared private, it cannot be accessed by anyone outside the class, thereby hiding the fields within the class. For this reason, encapsulation is also referred to as data hiding.

Encapsulation can be described as a protective barrier that prevents the code and data being randomly accessed by other code defined outside the class. Access to the data and code is tightly controlled by an interface.

The main benefit of encapsulation is the ability to modify our implemented code without breaking the code of others who use our code. With this feature Encapsulation gives maintainability, flexibility and extensibility to our code.

Example:

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public class EncapsulationBean{

   private String name;

   private String id;

   private int age;

   public int getAge(){

      return age;

   }

   public String getName(){

      return name;

   }

   public String getId(){

      return id;

   }

   public void setAge( int newAge){

      age = newAge;

   }

   public void setName(String newName){

      name = newName;

   }

   public void setId( String newId){

      id = newId;

   }

}

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In this class, fields are private so public methods are the access points to this class's fields from the outside java world. Normally these methods are referred as getters and setters. Therefore any class that wants to access the private variables, it should access them through these getters and setters methods.

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public class EncapsulationTest{

   public static void main(String args[]){

      EncapsulationBean encapBean = new EncapsulationBean();

      encapBean.setName("Krishna");

      encapBean.setAge(30);

      encapBean.setId("12527");

      System.out.print("Name:"+encapBean.getName()+"Age:"+
      encapBean.getAge());

    }

}

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Advantages of Encapsulation:

If you want maintainability, flexibility, and extensibility (and I guess, you do), your design must include encapsulation. How do you do that?

• Keep instance variables protected (with an access modifier, mostly private).
• Make public accessor methods, and force calling code to use those methods rather than directly accessing the instance variable.
• For the methods, use the JavaBeans naming convention of set and get.

1.  Encapsulated Code is more flexible and easy to change with new    requirements.
2.  Encapsulation in Java allows you to control who can access what.
3.  A class can have total control over what is stored in its fields

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