CalculatingLoanPayment.java

package Solutions;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

//we are calculating the loan payment for different banks like HDFC, ICICI, SBI etc.

interface Bank {
	String getBankName();
}

class HDFC implements Bank {
	private final String BNAME;

	public HDFC() {
		BNAME = "HDFC BANK";
	}

	public String getBankName() {
		return BNAME;
	}
}

class ICICI implements Bank {
	private final String BNAME;

	ICICI() {
		BNAME = "ICICI BANK";
	}

	public String getBankName() {
		return BNAME;
	}
}

class SBI implements Bank {
	private final String BNAME;

	public SBI() {
		BNAME = "SBI BANK";
	}

	public String getBankName() {
		return BNAME;
	}
}

abstract class Loan {
	protected double rate;

	abstract void getInterestRate(double rate);

	public void calculateLoanPayment(double loanamount, int years) {
		/*
		 * to calculate the monthly loan payment i.e. EMI
		 * 
		 * rate=annual interest rate/12*100; n=number of monthly installments;
		 * 1year=12 months. so, n=years*12;
		 * 
		 */

		double EMI;
		int n;

		n = years * 12;
		rate = rate / 1200;
		EMI = ((rate * Math.pow((1 + rate), n)) / ((Math.pow((1 + rate), n)) - 1)) * loanamount;

		System.out.println("your monthly EMI is " + EMI + " for the amount" + loanamount + " you have borrowed");
	}
}

class HomeLoan extends Loan {
	public void getInterestRate(double r) {
		rate = r;
	}
}

class BussinessLoan extends Loan {
	public void getInterestRate(double r) {
		rate = r;
	}

}

class EducationLoan extends Loan {
	public void getInterestRate(double r) {
		rate = r;
	}
}

abstract class AbstractFactory {
	public abstract Bank getBank(String bank);

	public abstract Loan getLoan(String loan);
}

class BankFactory extends AbstractFactory {
	public Bank getBank(String bank) {
		if (bank == null) {
			return null;
		}
		if (bank.equalsIgnoreCase("HDFC")) {
			return new HDFC();
		} else if (bank.equalsIgnoreCase("ICICI")) {
			return new ICICI();
		} else if (bank.equalsIgnoreCase("SBI")) {
			return new SBI();
		}
		return null;
	}

	public Loan getLoan(String loan) {
		return null;
	}
}

class LoanFactory extends AbstractFactory {
	public Bank getBank(String bank) {
		return null;
	}

	public Loan getLoan(String loan) {
		if (loan == null) {
			return null;
		}
		if (loan.equalsIgnoreCase("Home")) {
			return new HomeLoan();
		} else if (loan.equalsIgnoreCase("Business")) {
			return new BussinessLoan();
		} else if (loan.equalsIgnoreCase("Education")) {
			return new EducationLoan();
		}
		return null;
	}

}

class FactoryCreator {
	public static AbstractFactory getFactory(String choice) {
		if (choice.equalsIgnoreCase("Bank")) {
			return new BankFactory();
		} else if (choice.equalsIgnoreCase("Loan")) {
			return new LoanFactory();
		}
		return null;
	}
}

public class CalculatingLoanPayment {

	public static void main(String args[]) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		System.out.print("Enter the name of Bank from where you want to take loan amount: ");
		String bankName = br.readLine();

		System.out.print("\n");
		System.out.print("Enter the type of loan e.g. home loan or business loan or education loan : ");

		String loanName = br.readLine();
		AbstractFactory bankFactory = FactoryCreator.getFactory("Bank");
		Bank b = bankFactory.getBank(bankName);

		System.out.print("\n");
		System.out.print("Enter the interest rate for " + b.getBankName() + ": ");

		double rate = Double.parseDouble(br.readLine());
		System.out.print("\n");
		System.out.print("Enter the loan amount you want to take: ");

		double loanAmount = Double.parseDouble(br.readLine());
		System.out.print("\n");
		System.out.print("Enter the number of years to pay your entire loan amount: ");
		int years = Integer.parseInt(br.readLine());

		System.out.print("\n");
		System.out.println("you are taking the loan from " + b.getBankName());

		AbstractFactory loanFactory = FactoryCreator.getFactory("Loan");
		Loan l = loanFactory.getLoan(loanName);
		l.getInterestRate(rate);
		l.calculateLoanPayment(loanAmount, years);
	}

}