return three values from a while loop

[Rand Thomson]

I registered on this site since it's a friendly place for programming greenhorns of which I am definitely a newbie! I hope someone can help with this, I am using this while loop

while (loanBalance > 0)    
        MortgageBalance balance = new MortgageBalance((customInterest), interest1, principle1, payment1, loanBalance);
        //begin output and then calculate new variables
        outputTextArea.append(loancounter +
                         "                    " + df.format(payment1) + "       " + df.format(interest1) +
                         "         " + df.format(principle1) + "          " + df.format(loanBalance) + newline);
        interest1 = balance.interest();
        principle1 = balance.principle();
        loanBalance= balance.loanBalance();
        loancounter++;
    }

and I want to return three values from the loop, the interest1, principle1, and loancounter. I've gotten an idea from another forum that I could do these calculations in a method and return an arraylist from there but I'm very confused on what this means. I can post my entire program if it's needed, but basically I'm at a bit of a loss how to create a class and method, or just a method for the existing class where I can return elements of an arraylist, from there I need to manipulate the arraylist but I think I can handle that. What I'm doing is creating an amoritization table for a loan here, and I can't figure out how to take my existing classes and create the loop to calculate the amoritization table without how I have the while loop currently setup? Does this make sense, been looking at this for about 12 hrs now and I'm having a difficult time moving forward... Thanks for any help provided!

[Rahul Sudip Bose]

It would be convenient if you could give a brief description of your program and post the entire source code.
I dont know what is this code doing. The simplest solution that comes to my mind is that you can either dump the three values into an array (why ArrayList ?) and return a reference to the array.
OR (if its logical and suits your situation) you can make an Class with those three variables and methods to alter/access them and return a reference to that instance of that class.

wait a little more, i am sure you will get replies from more experienced people.
regards
rb

[Rand Thomson]

Here is the entire code, it's a gui so there's a lot of that there,

import javax.swing.*;
import javax.swing.JList.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.lang.String.*;
import java.util.*;
import java.text.*;
import java.io.*;

public class MCGGraph extends JFrame {

    /** Creates new form MCGJFrame */
    public MCGGraph() {
        initComponents();
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {
      
      try{
        
       //Create arrays for loan variables held in lists
        final String terms[] = {"7 years", "15 years", "20 years","25 years",  "30 years"};
        final String interests[] = {"5.0%", "5.35%", "5.5%", "5.75%", "6.00%"};
        final String loans[] = {"$100,000", "$150,000", "$200,000", "$250,000", "$300,000"};

        termListScrollPane = new JScrollPane(termList);
        termList = new JList(terms);
        interestListScrollPane = new JScrollPane( interestList);
         interestList = new JList(interests);
        loanTotalScrollPane = new JScrollPane( loanTotalList);
         loanTotalList = new JList(loans);
        outputScrollPane = new JScrollPane();
        outputTextArea = new JTextArea();
        calculateButton = new JButton();
        resetButton = new JButton();
        graphScrollPane = new JScrollPane();
        graphPanel = new JPanel();
        graphInterestButton = new JButton();
        graphPrincipleButton = new JButton();
        graphBothButton = new JButton();
        graphingInstructionsLabel = new JLabel();
        programInstructionsLabel = new JLabel();
        loanTotalTextField = new JTextField();
        interestTextField = new JTextField();
        termTextField = new JTextField();

        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        
        //Set list selection modes
        termList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
         interestList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
         loanTotalList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
            
        termListScrollPane.setViewportView(termList);

        interestListScrollPane.setViewportView(interestList);

        loanTotalScrollPane.setViewportView(loanTotalList);

        outputTextArea.setColumns(20);
        outputTextArea.setRows(5);
        outputScrollPane.setViewportView(outputTextArea);
        
        //Add selection listeners for lists, translate choices into useable values for text fields with if statements
        termList.addListSelectionListener(new ListSelectionListener(){
          public void valueChanged(ListSelectionEvent le) {
          //Get index of Selection
            int termIdx = termList.getSelectedIndex();
            //Translate choices into doubles for text boxes
            if (termIdx == 0) {
              termTextField.setText("7");
            } else if (termIdx == 1) {
              termTextField.setText("15");
            }
            else if (termIdx == 2) {
              termTextField.setText("20");
            }
            else if (termIdx == 3) {
              termTextField.setText("25");
            }
            else if (termIdx == 4) {
              termTextField.setText("30");
            }
          }
        });
        
        interestList.addListSelectionListener(new ListSelectionListener(){
          public void valueChanged(ListSelectionEvent le) {
          //Get index of Selection
            int interestIdx = interestList.getSelectedIndex();
            //Translate choices into doubles for text boxes
            if (interestIdx == 0) {
              interestTextField.setText("5.00");
            } else if (interestIdx == 1) {
              interestTextField.setText("5.35");
            }
            else if (interestIdx == 2) {
              interestTextField.setText("5.5");
            }
            else if (interestIdx == 3) {
              interestTextField.setText("5.75");
            }
            else if (interestIdx == 4) {
              interestTextField.setText("6.0");
            }
          }
        });
        
        loanTotalList.addListSelectionListener(new ListSelectionListener(){
          public void valueChanged(ListSelectionEvent le) {
          //Get index of Selection
            int loanIdx = loanTotalList.getSelectedIndex();
            //Translate choices into doubles for text boxes
            if (loanIdx == 0) {
              loanTotalTextField.setText("100000");
            } else if (loanIdx == 1) {
              loanTotalTextField.setText("150000");
            }
            else if (loanIdx == 2) {
              loanTotalTextField.setText("200000");
            }
            else if (loanIdx == 3) {
              loanTotalTextField.setText("250000");
            }
            else if (loanIdx == 4) {
              loanTotalTextField.setText("300000");
            }
          }
        });

        calculateButton.setText("Calculate");
        calculateButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                calculateButtonActionPerformed(evt);
            }
        });

        resetButton.setText("  Reset  ");
        resetButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                resetButtonActionPerformed(evt);
            }
        });

        GroupLayout graphPanelLayout = new GroupLayout(graphPanel);
        graphPanel.setLayout(graphPanelLayout);
        graphPanelLayout.setHorizontalGroup(
            graphPanelLayout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGap(0, 532, Short.MAX_VALUE)
        );
        graphPanelLayout.setVerticalGroup(
            graphPanelLayout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGap(0, 473, Short.MAX_VALUE)
        );

        graphScrollPane.setViewportView(graphPanel);

        graphInterestButton.setText("Graph Interest");
        graphInterestButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                graphInterestButtonActionPerformed(evt);
            }
        });

        graphPrincipleButton.setText("Graph Principle");
        graphPrincipleButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                graphPrincipleButtonActionPerformed(evt);
            }
        });

        graphBothButton.setText("Graph Both");
        graphBothButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                graphBothButtonActionPerformed(evt);
            }
        });

        graphingInstructionsLabel.setText("Please push a button to");

        programInstructionsLabel.setText(
                                "This application will compute the amoritization table for a loan" + 
                                " and graph the interest and principle paid on the loan. Please choose values from the lists, or");

        loanTotalTextField.setText("                   ");

        interestTextField.setText("                   ");

        termTextField.setText("                   ");

        GroupLayout layout = new GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGroup(GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.TRAILING)
                    .addComponent(programInstructionsLabel, GroupLayout.DEFAULT_SIZE, 1125, Short.MAX_VALUE)
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                            .addComponent(outputScrollPane, GroupLayout.DEFAULT_SIZE, 386, Short.MAX_VALUE)
                            .addGroup(layout.createSequentialGroup()
                                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING, false)
                                    .addComponent(loanTotalScrollPane)
                                    .addComponent(loanTotalTextField))
                                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                                    .addGroup(layout.createSequentialGroup()
                                        .addComponent(interestTextField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                        .addPreferredGap(LayoutStyle.ComponentPlacement.UNRELATED)
                                        .addComponent(termTextField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                    .addGroup(layout.createSequentialGroup()
                                        .addComponent(interestListScrollPane, GroupLayout.PREFERRED_SIZE, 85, GroupLayout.PREFERRED_SIZE)
                                        .addPreferredGap(LayoutStyle.ComponentPlacement.UNRELATED)
                                        .addComponent(termListScrollPane, GroupLayout.PREFERRED_SIZE, 85, GroupLayout.PREFERRED_SIZE)
                                        .addPreferredGap(LayoutStyle.ComponentPlacement.UNRELATED)
                                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING, false)
                                            .addComponent(resetButton, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                            .addComponent(calculateButton, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))))))
                        .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.TRAILING)
                            .addComponent(graphingInstructionsLabel, GroupLayout.DEFAULT_SIZE, 175, Short.MAX_VALUE)
                            .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING, false)
                                .addComponent(graphInterestButton, GroupLayout.Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                .addComponent(graphBothButton, GroupLayout.Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                .addComponent(graphPrincipleButton, GroupLayout.Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
                        .addGap(18, 18, 18)
                        .addComponent(graphScrollPane, GroupLayout.DEFAULT_SIZE, 534, Short.MAX_VALUE)))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(programInstructionsLabel, GroupLayout.PREFERRED_SIZE, 42, GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                    .addComponent(graphScrollPane, GroupLayout.DEFAULT_SIZE, 475, Short.MAX_VALUE)
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                            .addGroup(layout.createSequentialGroup()
                                .addComponent(calculateButton)
                                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(resetButton))
                            .addComponent(termListScrollPane, 0, 0, Short.MAX_VALUE)
                            .addComponent(interestListScrollPane, 0, 0, Short.MAX_VALUE)
                            .addComponent(loanTotalScrollPane, 0, 0, Short.MAX_VALUE))
                        .addGap(18, 18, 18)
                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.TRAILING)
                            .addGroup(layout.createSequentialGroup()
                                .addComponent(graphingInstructionsLabel, GroupLayout.PREFERRED_SIZE, 108, GroupLayout.PREFERRED_SIZE)
                                .addGap(12, 12, 12)
                                .addComponent(graphInterestButton)
                                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(graphPrincipleButton)
                                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(graphBothButton))
                            .addGroup(layout.createSequentialGroup()
                                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                                    .addComponent(loanTotalTextField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                    .addComponent(interestTextField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                    .addComponent(termTextField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                .addGap(21, 21, 21)
                                .addComponent(outputScrollPane, GroupLayout.PREFERRED_SIZE, 342, GroupLayout.PREFERRED_SIZE)))))
                .addContainerGap())
        );

        pack();
      }
    
 catch (Exception e) {
        System.err.println("Could not create GUI, something is very wrong, please try again");
      }
    }

    private void graphPrincipleButtonActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
    }

    private void graphBothButtonActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
    }

    // Variables declaration - do not modify
    public JButton calculateButton;
    public JButton graphBothButton;
    public JButton graphInterestButton;
    public JPanel graphPanel;
    public JButton graphPrincipleButton;
    public JScrollPane graphScrollPane;
    public JLabel graphingInstructionsLabel;
    public JList interestList;
    public JScrollPane interestListScrollPane;
    public JTextField interestTextField;
    public JScrollPane outputScrollPane;
    public JTextArea outputTextArea;
    public JList loanTotalList;
    public JScrollPane loanTotalScrollPane;
    public JTextField loanTotalTextField;
    public JLabel programInstructionsLabel;
    public JButton resetButton;
    public JList termList;
    public JScrollPane termListScrollPane;
    public JTextField termTextField;
    // End of variables declaration

    public final static String newline = "\n";
    // End of variables
    
    public class MortageCalc
{
    //Declare variables which make up loan
    double interestRate;
    double term;
    double loanAmount;
  
  
    //Constructor to create Mortgage instance
    public MortageCalc (double iR, double t, double lA)
    {
      interestRate = iR;
      term = t;
      loanAmount = lA;
    }
  
    //Method to determine Monthly payment
        double payment() {
            return loanAmount * (((interestRate)/12) * (Math.pow((1+((interestRate)/12)),
                                     (term * 12))))/(Math.pow((1+(((interestRate)/12))),(term * 12) )-1); //Monthrate = loan * [c(1+c)^n]/[(1 + c)^n -1] Determine monthly rate
        }
        //Method to determine First Interest Payment
        double monthInterest(){
           return loanAmount * (interestRate/12);
        }
        //Method to Determine First Principle Payment
        double monthPrinciple(){
          return payment() - monthInterest();
        }
        public double getInterest(){
          return interestRate;
        }
    }        
        
  public class MortgageBalance {
          double interestRateFull, interest, principle, payment, loanRemainder;
          MortgageBalance(double intrF, double intr, double princ, double pay, double loanR)
          {
            interestRateFull = intrF;
            interest = intr;
            principle = princ;
            payment = pay;
            loanRemainder = loanR;
          }
          
          
          //Calculate interest payed per payment
        double interest() {
          return loanRemainder * (interestRateFull/12);
        }
        
        //Calculate principle payed per payment
        double principle() {
          return payment - interest();
        }
        //Calculate loan remainder
        double loanRemainder(){
          return ((200000 * (1 + (interestRateFull/12))) - payment);
        }
        //Calculate loan remainder after first run
        double loanBalance(){
        return ((loanRemainder * (1 + (interestRateFull/12))) - payment);
        }
        
       
  }
  
  
   //Set behavior of clear button, used to clear form
    private void resetButtonActionPerformed(ActionEvent evt) {
       loanTotalList.clearSelection();
      termList.clearSelection();
       interestList.clearSelection();
      interestTextField.setText("");
      loanTotalTextField.setText("");
      termTextField.setText("");
      outputTextArea.setText("");
      }
    //Set behaviour of submit button to create loan and print amoritization table
    public void calculateButtonActionPerformed(ActionEvent evt) {
      
        try{
      //First clear JTextArea
      outputTextArea.setText("");
      
      //Declare variables
      double payment1;
      double customInterest = Double.parseDouble(interestTextField.getText())/100;
      double customTerm = Double.parseDouble(termTextField.getText());
      double customLoan = Double.parseDouble(loanTotalTextField.getText());
  
      //Create array with loan variables
      double [] loans = new double [3];
      loans [0] = customInterest;
      loans [1] = customTerm;
      loans [2] = customLoan;
      
      
      //Create new loan instances and calculate monthly payments
      MortageCalc m1 = new MortageCalc (loans [0], loans [1], loans [2]);
      payment1 = m1.payment();
      
      DecimalFormat df = new DecimalFormat("$###,###.##");
      outputTextArea.append("For a loan of " + df.format(customLoan) + 
                                     ". With a Term of " + customTerm + " years, and an interest rate of %" + customInterest + newline);
      outputTextArea.append(
                                    "The monthly payment for the loan is" + df.format(payment1) + newline);
      outputTextArea.append(
                                   "The Amoritization table for the loan is shown below" + newline);
      outputTextArea.append(
                                   "+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++"
                                   + newline);
      outputTextArea.append("Payment #        Payment        Interest        Principle        Balance" + newline);
      double loanBalance = ((customLoan * (1 + ((customInterest)/12))) - payment1);
      double interest1 = m1.monthInterest();
      double principle1 = m1.monthPrinciple();
      int loancounter = 1;
      ArrayList<Double> interestArrayList = new ArrayList<Double>();
      
      //While loop to create amoritization table
      while (loanBalance > 0){  
        if (loancounter <= customTerm * 12){
          interestArrayList.add(interest1);}
        MortgageBalance balance = new MortgageBalance((customInterest), interest1, principle1, payment1, loanBalance);
        //return variables to arrays
       // outputTextArea.append(loancounter + "                    " + df.format(payment1) +
                       "       " + df.format(interest1) + "         " + df.format(principle1) +
                       "          " + df.format(loanBalance) + newline);
        interest1 = balance.interest();
        principle1 = balance.principle();
        loanBalance= balance.loanBalance();
        loancounter++;
        
        
        
        /**double sumPrinciple = 0;
        for(int i=0; i < principleList.size(); i++){
            sumPrinciple = sumPrinciple +(principleList.get(i));
        }
        
        double sumInterest = 0;
        for(int i=0; i < interestList.size(); i++){
            sumInterest = sumInterest + (interestList.get(i));
        }
        
        System.out.println(sumInterest);
        **/
    }
     }
        
        //Catch exceptions print out error message
        catch (NumberFormatException e){
      outputTextArea.append("Oops you've broken me, cough, cough, hack, gasp, I'm dying...." + newline);
      outputTextArea.append(
                        "It's likely something in the entry fields is malformed, entries in text boxes should be formatted as described." + newline);
      outputTextArea.append("Please try again...Cough, cough, hack, gasp...");
      }

    }
    
    private void graphInterestButtonActionPerformed(ActionEvent evt) {
          
    }
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new MCGGraph().setVisible(true);
            }
        });
    }

}

There is extraneous code in there as I've been looking at it and commenting out sections and whatnot. I get that the event listener is a void, so I can't return anything out of there, so how can I modify the code to produce the three variables per iteration of the while loop to create an array, or arraylist? I went with arraylist since the different variables will not create an array with a set value for the number of rows, though I suppose I could create the array like

double loanStuff[] = new double [customTerm*12][3]

, right? Basically I want to take all the answers from the amoritization table for interest and principle paid, and sum them and then create a pie chart out of those answers. I think I can figure out how to do that, but I'm having a heck of a time figuring out how to return what I want from the while loop.

[Rob Spoor]

Rand Thomson wrote:Here is the entire code, it's a gui so there's a lot of that there,
...
There is extraneous code in there

So trim it down and create an SSCCE. Leave out any component that's not relevant. Use shorter message strings. And keep it as small as possible.

[Campbell Ritchie]

. . . and welcome to the Ranch

[Paul Clapham]

Bear in mind that I didn't read the big blob of code; but you don't "return a value from a loop" in Java. It would certainly be possible for the loop to assign a value to a variable which is declared outside the loop, and you might think of that as "returning a value". If that's what you had in mind, it would also be possible for the loop to assign values to three variables which are declared outside the loop.

However if that wasn't what you had in mind, go ahead and post the SSCCE.

[Rand Thomson]

Paul, that will work great. How would I do that?

[fred rosenberger]

//blah blah blah...
int x = 0;

for (int i = 0; i< 10; i++)
{
   x +=i;
}
//you can now use the value of x

[Rand Thomson]

Thanks!