Encapsulation

Objective

In this lab, we will demonstrate Encapsulation in the Java language. By the end of this lab, learners will be able to use Encapsulation.

Introduction to Encapsulation in Java

Encapsulation refers to hiding the class variable from other classes and giving access to them only through methods (setters and getters).

Encapsulation in Java means binding the data (variables) with the code (methods – setters and getters). The below diagram depicts Encapsulation in Java.

💡 Points of the above diagram:

• Class Variables (in the example: height, weight, and bmi) are declared private; hence, they are not visible to other classes.

• For each variable, there is a setter and getter method, which sets a value to the variable and gets the variable's value, respectively.

• Example: For variable height, setter method is setHeight() and getter method is getHeight().

• Setter and Getter methods are public; hence, they are visible to other classes.

A Program Example

Create a class named HumanBeing with two constructors: class variables (weight, height, and bmi) and setter and getter methods.

public class HumanBeing {

   private float weight;
   private float height;
   private float bmi;

   public HumanBeing(float weight, float height, float bmi )
   {
       this.weight = weight;
       this.height = height;
       this.bmi = bmi;
   }
   public HumanBeing()
   {

   }
   public float getWeight() {
       return weight;
   }
   public void setWeight(float weight) {
       this.weight = weight;
   }
   public float getHeight() {
       return height;
   }
   public void setHeight(float height) {
       this.height = height;
   }
   public float getBmi() {
       return bmi;
   }
   public void setBmi(float bmi) {
       this.bmi = bmi;
   }
}

Create a class named EncapsulationExample, with a main() method.

public class EncapsulationExample {
   public static void main(String[] args) {
       HumanBeing h1 = new HumanBeing();
       // using setters of HumanBeing
       h1.setHeight(1.65f);
       h1.setWeight(68);
       h1.setBmi(calculateBmi(h1));

       // using getters of HumanBeing
       System.out.println("Person has "+h1.getWeight()+" kgs and is "+h1.getHeight()+" meters in height, which results in BMI of "+h1.getBmi());
   }

   public static float calculateBmi(HumanBeing h1){
       return h1.getWeight()/(h1.getHeight()*h1.getHeight());
   }
}

Run/compile your Code,

Output

Person has 68.0 kgs and is 1.65 meters in height, which results in BMI of 24.977045

1KB

GLAB - 303.9.1 - Encapsulation in Java.zip

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