You seem to be swimming Cassie.

By the looks of this problem, your instructor expects
you to understand method calls, loops, conditionals..
Your code displays little, if any of that understanding.

One answer to your question is displayed in the
following variant of your code.  It displays
defining and calling a method, and a switch
statement (conditional).

But we cannot run an entire Java course
through usenet though, so you are going
to need to hit the books and figure out
what these changes mean.

<sscce>
//importing classes
import java.lang.Math;
import java.text.NumberFormat;

// naming this class
public class Array2exp
{
 //calling Currency formatting
 static NumberFormat nf = NumberFormat.getCurrencyInstance();

 public static double amortization(int years) {
   // do the amortization calcualations..
   // ..  blah, blah
   double amount;
   switch(years) {
     case 7:
       amount = 0.4;
       break;
     case 15:
       amount = 0.6;
       break;
     case 30:
       amount = 0.8;
       break;
     default:
       amount = -1.0;
       System.out.println("!! Logic Error !!");
   }

   return amount;
 }

 public static double payment(int years) {
   // do the amortization calcualations..
   // ..  blah, blah
   return 1.0;
 }

    public static void main (String [] args)
    {
 // Array declration
 double mortgages [];
 double interest [];
 int term [];
 double amort [];
 double pay [];

 //Array creation
 mortgages = new double[3];
 interest = new double [3];
 term = new int [3];
 amort = new double [3];
 pay = new double [3];

 // Array initialization
 mortgages [0] =
(200000*5.35*(Math.pow((1+5.35/1200),84)))/(1200*(Math.pow((1+5.35/1200),84)-1));
 mortgages [1] =
(200000*5.5*(Math.pow((1+5.5/1200),180)))/(1200*(Math.pow((1+5.5/1200),180)-1));
 mortgages [2] =
(200000*5.75*(Math.pow((1+5.75/1200),360)))/(1200*(Math.pow((1+5.75/1200),360)-1));
 interest  [0] = 5.35;
 interest  [1] = 5.5;
 interest  [2] = 5.75;
 term [0] = 7;
 term [1] = 15;
 term [2] = 30;
 amort [0] = amortization(7);
 amort [1] = amortization(15);
 amort [2] = amortization(30);
 pay [0] = payment(7);
 pay [1] = payment(15);
 pay [2] = payment(30);

      //for loop, (initialization, expression, update)
      for (int MonthlyPayment=0; MonthlyPayment<=2; MonthlyPayment++)
      {
   //print statement
   System.out.print("$200,000 principle, ");
   System.out.print(interest[MonthlyPayment]);
   System.out.print("% interest, ");
   System.out.print(term[MonthlyPayment]);
   System.out.print(" years, ");
   System.out.println("Payment ");
   System.out.print(nf.format(mortgages[MonthlyPayment]));
   System.out.println("");
   System.out.println(pay[MonthlyPayment]);
   System.out.println(amort[MonthlyPayment]);
      }
    }
}
</sscce>

BTW, please do not cross-post.
<http://www.physci.org/codes/javafaq.jsp#xpost>
Since these sort of questions are best
dealt with on c.l.j.help, I will set
follow-ups to ge to that group alone.

HTH

This is a Good Thing(tm). Using a GUI very often obscures the things you are
trying to learn.

This suggestion *will* help your grade: the word is spelled "principal".

Do you need to do it this way? Are you allowed to include the computations
for these different scenarios in your program, or is the above a course
requirement?

About your program. You have all your code in a single method: main(). Try
breaking your code up into individual methods, this will greatly ease the
task of writing this or nearly any other program.

The question is whether you are permitted include the programs you describe.
If so, then yes, this is a better approach.

By the way, is using arrays a requirement? The problem you posed doesn't
rewquire them. If the lesson is about using arrays, go ahead as you are
doing, but if not, you may want to reconsider your approach.

(200000*5.35*(Math.pow((1+5.35/1200),84)))/(1200*(Math.pow((1+5.35/1200),84)-1));

(200000*5.5*(Math.pow((1+5.5/1200),180)))/(1200*(Math.pow((1+5.5/1200),180)-1));

(200000*5.75*(Math.pow((1+5.75/1200),360)))/(1200*(Math.pow((1+5.75/1200),360)-1));

Wow. Consider using program constants to describe the various parametes for
your computation, and I certainly advise that you write at least one method
to set up the mortgage initialization that you are now doing by copying a
code line and changing some numbers, as above.

Say again?