A simple implementation of OOP concepts in JAVA

Main.java

class Calculation {
  private int batteryLife = 10;
  int z;
  int w;
 
  public void addition(int x, int y) {
    z = x + y;
    System.out.println("The sum of the given numbers:"+z);
  }

  public void subtraction(int x, int y) {
    z = x - y;
    System.out.println("The difference between the given numbers:"+z);
  }

  public void subtraction(int x, int y, int z) {
    w = x - y + z;
    System.out.println("The addition of the difference between the first two numbers and third numbers:"+w);
  }
  
  public void displayResult(String message) {
    System.out.println("The Default Result of Calculation is:"+message);
  }

  public void setBatteryLife (int life) {
    batteryLife = life;
  }

  public double getBatteryLife () {
    return batteryLife;
  }
}

class My_Calculation extends Calculation {

  public void multiplication(int x, int y) {
    z = x * y;
    System.out.println("The product of the given numbers:"+z);
  }
  
  public void displayResult(String message) {
    System.out.println("The Dynamically Polymorphosed Result of Calculation is:"+message);
  }
 
}

class Main {
  public static void main(String[] args) {
    int a = 20, b = 10, c = 15;
    String d = "Some Dynamic Values", e = "Few Default Values";
    
    My_Calculation demo = new My_Calculation();
    demo.addition(a, b);
    demo.subtraction(a, b);
    demo.subtraction(a, b, c);
    demo.multiplication(a, b);
    demo.setBatteryLife(50);
    System.out.println("Battery Life is: "+(int)demo.getBatteryLife());
    demo.displayResult(d);
    
    Calculation baseClass = new Calculation();
    baseClass.displayResult(e);
    baseClass.setBatteryLife(60);
    System.out.println("Battery Life for the baseClass is: "+(int)baseClass.getBatteryLife());
  }
}

// Compile By: javac Main.java
// Run By: java Main

// OUTPUT:
// The sum of the given numbers:30
// The difference between the given numbers:10
// The addition of the difference between the first two numbers and third numbers:25
// The product of the given numbers:200
// Battery Life is: 50
// The Dynamically Polymorphosed Result of Calculation is:Some Dynamic Values
// The Default Result of Calculation is:Few Default Values
// Battery Life for the baseClass is: 60

The working code can be seen on this REPL