Need help with my first program

[supahsain08]

Use code (or syntax) tags! - wtd

Hello, I started java couple of weeks ago, and i know almost nothing about it

My teacher gave us our first java assignment couple of weeks go

We are suppose to make a program which calculate and print out the interest for each month for one year (12 months), then add the interest to the principal to get a new total and print out the new total principle.

My proggy

Java:

class work {     public static void main(String[] args)     {     double interestrate, principal, interest, time, total;            interestrate = 0.12;    principal = 100.0;    time = 0.083;        interest = interestrate * principal * time ;       total = interestrate * principal * time + principal; int n;    for (n = 1; n <= 12; n = n +1) {          System.out.println("The interest for month " + n + " is "+ interest);         }       } }

the problem is i don't know how to put interest and principle in a for loop too
any hints will be appreciated

[HeavenAgain]

Quote:

put interest and principle in a for loop

just do what you just said, but i dont think "principal" needs to be added in, only the interest and total.........

Ps. your total should only be your interest (for every month) + the initial amount deposit , unless im wrong...

[supahsain08]

That's my Assignment
This following requirements must be met by the program you write:

Your program should do the following:

* create some variables named interestrate, principal, interest, time, and total (all numbers should be doubles).
* Set the values of the variables interestrate, and principal, to some appropriate numbers (interestrate should be between 0.0 and 1.0)
* Use a for loop to calculate and print out the interest for each month for one year (12 months), then add the interest to the principal to get a new total and print out the new total principle.


Here's my code

code:

import java.text.*; public class asn1 {     public static void main(String[] args)       {                         double interestrate, principal, interest, time, total;         int month;         String pattern1 = "#.##";         String pattern2 = "###.##";         DecimalFormat x = new DecimalFormat(pattern1);         DecimalFormat y = new DecimalFormat(pattern2);                  interestrate = 0.12;         principal = 100;         time = 0.0833;         interest = interestrate * principal * time ;         System.out.println ("Initial Principle = " + principal);         System.out.println ("Interest Rate = " + interestrate);         for (month = 1; month <= 12; month = month + 1)         {         interest = interest + 0.01;         principal = principal + interest;         System.out.println ("The interest for month " + month + " is " + x.format(interest) + " and the total is " + y.format(principal));       } } }

This is what i don't understand, how am i suppose to calculate the interest each month, i know how to calculate for first month
I = 0.083 * 100 * .12 = 0.996
how do you find the interest for second and third month, what's the formula [/syntax]

[HeavenAgain]

what's the formula?
your teacher just gaved it to you. "interest = principal x rate x time"
in your case, "interest = interestrate * principal * time"
but in your for-loop, you have interest = interest + 0.01; , now what you did is instead of using the equation you have, you just add 0.01 to interest everytime (which is wrong), and after, you have principal = principal + interest; which just says, ok principal just add the interest, which is correct, IF you did your interest correct.

im not sure if you learned a runtime table or whatever it is called, where you follow your code line by line, and put the values in a table, it helps alot when you just begin to learn about loops, do that, and you'll see where you are wrong. (learn to read your own code, and follow it)

[supahsain08]

K did some more modifications

code:

import java.text.*; public class asn1 {   public static void main(String[] args)    {      // Declaring Double variables for calculations      double interestrate, principle, interest, time, total;      // Declaring int variable for months calculation      int month;      // Creating a pattern for outputing desired amount of decimals      String pattern1 = "#.00";      String pattern2 = "###.00";      DecimalFormat x = new DecimalFormat(pattern1);      DecimalFormat y = new DecimalFormat(pattern2);            // Initializing values for the variables         interestrate = 0.120;      principle = 100.0;      time = 0.0833;      interest = interestrate * principle * time ;      System.out.println ("Initial Principle = " + principle);      System.out.println ("Interest Rate = " + interestrate);            // Skipping two lines         System.out.println("\n");      System.out.println("\n");            // Using a for loop for months      for (month = 1; month <= 12; month++)              {      // Using for loop to calculate principle      principle = principle + interest;      // Outputing all the Calculations      System.out.println ("The interest for month " + month + " is $" +x.format(interest) + " and the new total is $" + y.format(principle));      // Using for loop to calculate interest      interest = interestrate * principle * time;      }    } }

Output


any mistake?

[HeavenAgain]

if i were to be picky about it, your output did not exactly match your teacher's output, the Initial Principle = 100.00 you are missing another 0 on the end, so format that properly, and also

code:

// Skipping two lines         System.out.println("\n");      System.out.println("\n");

what this does, is not just skip "two" lines, it skiped 4 lines, you have a system.out.println() which already prints 1 line, and in it you are printing another line with "\n"....

[syntax_error]

instead of asking us; do the math on paper first and think; you will answer your own questions that way; be self aware a bit more.

On a side note your class names should have the first letter in CAPS

[supahsain08]

Thanks HeavenAgain
@ syntax_error: I don't have the first letter in caps because my teacher said file name should be "asn1.java"

[syntax_error]

oo well good coding conventions state: have the first letter of your class in CAPS; jsut keep in as reference for work maybe not for your teacher?