Encapsulation

Most of you heard the word 'Encapsulation' while dealing with Java OOPs concepts. What it stands for?

We will start with an example. Imagine you have made your class with public instance variables as shown below.

public class Sample{
public int height;
public int weight;
}
public class MainClass{
public static void main(String args[]){
Sample sample = new Sample();
sample.height = 170;
}


You have created this class and think that many of others used this class for setting height and weight variables directly. Now you are really in trouble. Just think a situation that you want to do something when someone set height variable?. Can you do that without breaking everyone's code?

Here comes encapsulation. It helps to change your implemented code without breaking the code of others who use your code. You must follow encapsulation if you want maintainability , flexibility and extensibility.

• Instance variables must be private or protected.
  
• To change an instance variable , use public accessor methods , and force others to use this
  methods to change the variable.

The above example can be changed to include encapsulation

public class Sample{
private int height;
private int weight;

public void setHeight(int height){
this.height = height;
}

public void setWeight(int weight){
this.weight= weight;
}

public int getHeight(){
return height;'
}

public int getWeight(){
return weight;'
}
}

public class MainClass{
public static void main(String args[]){
Sample sample = new Sample();
sample.setHeight(170); // User forced to use the public method to set value
}


Hope you got an idea about encapsulation... :)