// 1. Code Reuse
class Account
{
	int acno;
	float bal;
	void deposit()
	{
		System.out.println("Accout Class Deposit Call ");	
	}
	void withdraw()
	{
		System.out.println("Accout Class W Draw Call ");
	}
	}
	class SavingAc extends Account
	{
		void roi()
		{
			System.out.println("Saving Ac ROI Call ");
		}
	}
	class CurrentAc extends Account
	{
		void roi()
		{
			System.out.println("Current Ac ROI Call ");
		}
	}
	class TestBank
	{
		public static void main(String agrs[])
		{
			CurrentAc obj = new CurrentAc();
			obj.deposit();
			obj.withdraw();
			obj.roi();
			SavingAc obj1 = new SavingAc ();
			obj1.deposit();
			obj1.withdraw();
			obj1.roi();
		}
} 

Accout Class Deposit Call 
Accout Class W Draw Call 
Current Ac ROI Call 
Accout Class Deposit Call 
Accout Class W Draw Call 
Saving Ac ROI Call

class person  
{  
    int age;  
    String name;  
    String address;  
}  
class Customer extends person  
{  
    int custId;  
    int custno;  
    void customerInput()  
    {  
        name="shalabh";  
        age=20;  
        address="mumbai";  
        custno=02;  
        custId=1001;  
    }  
    void print()  
    {  
        System.out.println("customer name = "+name);      
        System.out.println("customer age = "+age);  
        System.out.println("customer address = "+address);  
        System.out.println("customer no = "+custno);  
        System.out.println("customer id = "+custId);  
    }  
}  
public class Test  
{  
    public static void main(String s1[])  
    {  
        Customer customer=new Customer();  
        customer.input();  
        customer.print();  
    }  
}  

customer name = shalabh
customer age = 20
customer address = mumbai
customer no = 2
customer id = 1001

class Loan
{  
    public void emi()  
    {  
        System.out.println("inside Loan emi...");  
    }  
    public void details()  
    {  
        System.out.println("inside details...");  
    }  
}  
class HomeLoan{  
    Loan loan=new Loan();  
    public void emi()  
    {  
        loan.emi();  
    }      
}  
public class Test {  
    public static void main(String[] args)
    {  
        HomeLoan homeLoan=new HomeLoan();  
        homeLoan.emi();  
    }  
}  

inside Loan emi...

class Ac
{
	void deposit()
	{
		System.out.println("Account Class Deposit");
	}
	void withdraw()
	{
		System.out.println("Account Class Withdraw");
	}
}
class HDFC1 extends Ac
{
	void withdraw()  // Overriding
	{
		System.out.println("HDFC Class Withdraw");
	}
	void roi()
	{
		System.out.println("HDFC ROI ");
	}
}
class TestHDFC
{
	public static void main(String args[])
	{
		HDFC1 obj = new HDFC1();
		obj.deposit();
		obj.withdraw();
		obj.roi();
	}
} 

Account Class Deposit
HDFC Class Withdraw
HDFC ROI

class A
{  
    int temp=10;  
    void show()  
    {  
        System.out.println("A Show");  
    }  
}  
class B extends A
{  
    int temp=20;  
    void show(){  
    super.show();  //Use of super to call parent class method  
    System.out.println("B Show");  
    this.temp=super.temp+this.temp;  
    }  
}  
class Test
{  
    public static void main(String args[])
    {  
    	B obj=new B();  
    	obj.show();  
    }  
}  

A Show
B Show

class A
{  
     A()
      {  
        System.out.println("A Class Default Constructor Call");      
      }  
      A(int a)
      {  
        System.out.println("A class Parameterized Constructor call ");  
      }
}  
class B extends A
{  
	B()
	{ 
		System.out.println("B Class Default Constructor Call ");  
	}  
	B(int t)
	{  
		super(10); //Use of super to call parent class parameterized constructor and it must be the first line.  
		System.out.println("B Class Parameterized Constructor call");  
	}  
}  
class Demo
{
	public static void main(String args[])
	{
		B b=new B();
		A a=new A(10);
	}
}

A Class Default Constructor Call
B Class Default Constructor Call 
A class Parameterized Constructor call

class Add
{
	public int add(int x, int y)
	{
		return x + y;
	}
	// Overload the add() to add doubles instead of ints
	public double add(double x, double y)
	{
		return x + y;
	}
}

// From another class, invoke the add() method
public class Demo 
{
	public static void main (String [] args) 
	{
		Add a = new Add();
		int b = 27;
		int c = 3;
		int result = a.add(b,c); // Which add is invoked?
		double doubleResult = a.add(22.5,9.3); // Which add?
		System.out.println("result"+"  "+result);
		System.out.println("doubleResult"+" "+doubleResult);
	}
}

result  30
doubleResult 31.8

// UpCasting
// DownCasting
class S
{
	int x = 100; 
	void disp()
	{
		System.out.println("Disp of S ");
	}
}
class T extends S
{
	int x = 200;
	/*void disp()
	{
		System.out.println("Disp of T ");
	}*/
	void show()
	{
		System.out.println("Show of T ");
	}
}
public class CastingDemo 
{
	public static void main(String[] args) 
	{
		S obj = null;  // obj is a Reference Variable of type S
		//obj = new S();
		obj = new T(); // Create T object and pass the Reference to the obj
		//S obj = new T();  // Upcasting
		System.out.println("Upcasting Result is ");
		System.out.println("Value of X is "+obj.x);
		obj.disp();
		System.out.println("DownCasting Result is ");
		T obj2 = (T)obj;  // DownCasting
		obj2.show();
		obj2.disp();
	}
}

Upcasting Result is 
Value of X is 100
Disp of S 
DownCasting Result is 
Show of T 
Disp of S 

public class Demo 
{
    public Demo()
    {
        System.out.println("In default constructor...");
    }
    public Demo(int i)
    {
        this();
        System.out.println("In single parameter constructor...");
    }
    public Demo(int i,int j)
    {
        this(j);
        System.out.println("In double parameter constructor...");
    }
     
    public static void main(String a[])
    {
        Demo ch = new Demo(10,20);
    }
}

In default constructor...
In single parameter constructor...
In double parameter constructor...