Java OOPS – Part 2 – types of Inheritance with examples

Inheritance

Inheritance is a mechanism wherein a new class (child class) is derived from an existing class (parent class), child classes may inherit or acquire the properties and methods of parent classes.

Types of inheritance

• Single / multi level inheritance
• Hierarchical inheritance

Benefits of inheritance

• Reusability
• Extensibility
• Saves time and effort
• Provides clear model structure

For details, watch here

Code samples

Example – 1

Base Class – Animals

—-Child Class – Cat

—-Child Class – Lion

——–Child Class – Cub

package inheritanceEx;
public class Animals {
	int NoOfEyes = 2;	
	Animals(){
		System.out.println("Animals : -");
	}

	public void Eat() {
		System.out.println("I can eat");
	}
	
	public void Eyes() {
		System.out.println("I have "+ NoOfEyes + " eyes");
	}
}

package inheritanceEx;
public class Cat extends Animals{	
	void Meow() {
		System.out.println("Sound of cat - Meow");
	}

	public static void main(String[] args) {
		Cat cat = new Cat();
		cat.Eat();
		cat.Eyes();
		cat.Meow();
	}
}

package inheritanceEx;
public class Lion extends Animals{
	void Roar() {
		System.out.println("Sound of lion - Roar");
	}

	public static void main(String[] args) {
		Lion lion = new Lion();
		lion.Eat();
		lion.Eyes();
		lion.Roar();
		//lion.Meow(); //no relation between cat and lion
	}
}

package inheritanceEx;
public class Cub extends Lion{
	void Cooing() {
		System.out.println("Sound of Cub - Coo");
	}

	public static void main(String[] args) {
		Cub cub = new Cub();
		//super(); //error - should be 1st line of the method
		cub.Eat();
		cub.Eyes();
		cub.Cooing();
	}
}
//super() - refers to parent constructor

Example – 2

Base Class – BankAcc

—-Child Class – SavingsAcc

——–Child Class – Transactions

package inheritanceEx1;
public class BankAcc {
	
	String Cust_Name;
	int CustAcc_No;
	
	BankAcc(String Name, int AccNo){
		Cust_Name = Name;
		CustAcc_No = AccNo;
	}
	
	void DispCust() {
		System.out.println("Customer Name - " + Cust_Name);
		System.out.println("Customer Acc No - " + CustAcc_No);
	}
}

package inheritanceEx1;

public class SavingsAcc extends BankAcc{
	
	int Balance;
	int Min_Balance = 1000;
	
	SavingsAcc(String Name, int AccNo, int Bal){
		super(Name, AccNo); //	BankAcc(String Name, int AccNo){ from BankAcc
		Balance = Bal;
	}
	
	String isMinBalMaintained() {
		if(Balance > Min_Balance) {
			return "Yes";
		}
		else
			return "No";
	}
	
	void DispCust() {
		super.DispCust();
		System.out.println("Balance - " + Balance);
		System.out.println("Is Min Balance Maintained? - " + isMinBalMaintained());		
	}

	public static void main(String[] args) {
		SavingsAcc savingacc = new SavingsAcc("SKP", 4317625, 23400);
		savingacc.DispCust();
	}
}

package inheritanceEx1;

public class Transactions extends SavingsAcc{
	
	int Withdrawl;
	int Deposit;
	
	Transactions(String Name, int AccNo, int Bal, int exp, int deposit){
		super(Name, AccNo, Bal);
		Withdrawl = exp;
		Deposit = deposit;
		Balance  += deposit;
		Balance -= exp;
	}
	
	void DispCust() {
		super.DispCust();
		System.out.println("Total Withdrawls - " + Withdrawl);
		System.out.println("Total Deposits - " + Deposit);
	}

	public static void main(String[] args) {
		Transactions trans =  new Transactions("SKP", 7642398, 23400, 1200, 3400);
		trans.DispCust();
	}
}