loanrepay.java

loan Pay 一个用于计算银行利息的小程序。

import java.util.Scanner;

public class LoanRepay 
{
    public static void main(String[] args)
	{
    	Scanner keyboard = new Scanner (System.in);
    	float A,R,r,b,B;
	    int Y,M,i;
	    // A stands for the loan amount
	    // R stands for the monthly repayment
	    // r stands for the net annual interest rate(without %)
	    // Y stands for the number of whole remaining years
	    // M stands for the number of remaining months
	    
    	System.out.print("Please input the loan amount: $");
    	A = keyboard.nextFloat();
	    System.out.print("Please input the net annual interest rate(r%): r=");
	    r = keyboard.nextInt();
	    System.out.print("Please input the number of whole remaining years: Y=");
	    Y = keyboard.nextInt();
	    System.out.print("Please input the number of remaining months: M=");
	    M = keyboard.nextInt();
		// display the input requirements and the entered datas
	    
	    r = r/100;
	    b = 1+r;
	    B = 1;
	   
	    if (A>=0&&r>=0&&Y>=0&&M>=0)
	    {
	    	for (i=1 ; i<=Y ; i++)
	    	{
	    		B = B*b;
	    	}
	    	// calculate the (1+r)^Y
	    	
	    	R = (A*r*B*(12+r*M))/(12*(r*M+((12+r*M)*(B-1))));
	    	// use this formula to calculate the monthly repayment
	    	
	    	System.out.print("The monthly repayment R is $");
	    	System.out.printf("%.2f",R);
	    	
	    }
	    else 
	    {
			if (A<0)
                System.out.println("Some error message for the invalid amount!");
			if (r<0)
				System.out.println("Some error message for the invalid interest rate!");
			if (Y<0)
				System.out.println("Some error message for the invalid year(s)!");
			if (M<0)
				System.out.println("Some error message for the invalid months!");
			// when something wrong with the inputs, the relative information will be displayed on the screen
		
		}
	}		
}