Am i doing encapsulation correctly?

Question

I have tried a combination of abstract and encapsulation concepts. Can u guys please tell me whether there is any blunder in the following code. The code compiles very well. But i want to know my way of writing this java code.Please correct my code.... any better way of coding this..Expecting your suggestions..
public abstract class Shapes {
     public int length  = 0;
     public int breadth = 0;
public Shapes(){
     this.breadth = breadth;
     this.length = length;
public abstract int getLength();
public abstract int getBreadth();
public void calculateArea(int l,int b){
     System.out.println("Area  is "+(l*b));
public class Square extends Shapes{
     public Square(int length,int breadth){
          super.length = length;
          super.breadth = breadth;
     public int getBreadth(){
      return super.breadth;     
     public int getLength(){
          return super.length;
     public static void main(String args[]){
          Shapes a = new Square(23,37);
          a.calculateArea(a.getBreadth(),a.getLength());
}

Answer 1

Kannan_S wrote:
Can u please correct my code..so that maximum encapsulation is achieved.."Encapsulation" is sometimes referred to as "data-hiding", so any field that is declared public violates encapsulation (unless it's also final ); however, as prometheuzz pointed out, if you define eveything as private you'll have an unusable object. The trick is to provide only the access required to make something work. A few guidelines for you, until you know when you can open things up a bit more (I'll probably get shot down here, but here goes...):
1. Make all your instance fields private .
2. Provide a public constructor or factory method to allow clients to create objects (factory methods are sometimes better).
3. Provide public or protected "getter" methods for any field that needs to be read outside the class.
4. Provide public or protected "setter" methods for any field that needs to be updated outside the class.
    Note: before you make any of them public, make sure that it really does need to be updated outside the heirarchy.
5. Don't call any public methods from a constructor or factory method.
6. If a field only needs to be set once, at creation time, make it final.
7. Unless you know that a class is going to be subclassed, declare it final too. You can always change your mind later.
HIH