[Alex McQuaid]

I am trying to create a BB application that will generate a monthly payment table similar to the one that I am currently using in MS Excel. (copy of Excel Table is attached).

Here’s what I have created so far, and I would really appreciate it if you could show me what I am doing wrong. I want to have the application calculate and show the monthly payment amount automatically once the annual interest rate is inserted, and without the use of any button. I am having difficulty compiling the appication.

import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.FieldChangeListener;
import net.rim.device.api.ui.FocusChangeListener;
import net.rim.device.api.ui.component.EditField;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.text.TextFilter;
import net.rim.device.api.ui.text.NumericTextFilter;
import net.rim.device.api.ui.container.MainScreen;

public class TableScreen extends MainScreen implements FieldChangeListener,FocusChangeListener {


/// USER INPUT ///
EditField custnbrField; /// 1234567890
EditField principalField; /// $10,000.00
EditField annintrateField; //// 10.00%
EditField amortprdField; /// 3

/// CALCULATIONS ///
EditField effannintrateField; // ROUND((1+mthlyintfactor)^12-1,4)....Result = 10.25%
EditField mthlyintfactorField; // ((1+(annintrate/2))^2)^(1/12)-1).....Result = 0.008164846%
EditField mthsamortField; // amortprd*12......Result = 36 mths
EditField mthlypaymentField; // (principal * mthlyintfactor)/(1-(1+mthlyintfactor)^(-mthsamort)).....Result = $321.7234593
EditField rndnearestcentField; // ROUND(mthlypayment,2).....Result = $321.72
EditField rndnearestdollarField; // ROUND(rndnearestcent,0)..... Result = $322.00

public TableScreen() {
TextFilter numeric = new NumericTextFilter(NumericTextFilter.ALLOW_DECIMAL) ;
custnbrField = new EditField("Customer Number: " , "");
custnbrField.setFilter(TextFilter.get(TextFilter.N UMERIC)); // no decimal
add(custnbrField);

principalField = new EditField("Initial Principal: $ " , "");
add(principalField);

annintrateField = new EditField("Annual Interest Rate: % " , "");
annintrateField.setFilter(numeric);
add(annintrateField);

amortprdField = new EditField("Amortization Period: (yrs) " , "");
amortprdField.setFilter(TextFilter.get(TextFilter. NUMERIC)); // no decimal
add(amortprdField);

effannintrateField = new EditField("Effective Annual Interest Rate: %" + aa );
effannintrateField.setFilter(numeric);
add(effannintrateField);

mthlyintfactorField = new EditField("Monthly Interest Factor: " + bb );
add(mthlyintfactorField);

mthsamortField = new EditField("Months to Amortization: "+ cc );
add(mthsamortField);


//// Monthly Payment to be displayed automatically after Monthly Interest Factor has been calculated
mthlypaymentField = new EditField("Periodic Monthly Payment: $"+ dd );
add(mthlypaymentField);

rndnearestcentField = new EditField("Rounded to nearest cent: $" + ee );
add(rndnearestcentField);

rndnearestdollarField = new EditField(("Rounded to nearest dollar:$" + ff );
add(rndnearestdollarField);

}
}
public void focusChanged(Field field, int eventType);
if (eventType == FOCUS_LOST) {
if (field == mthlypayment) {
float aa = ROUND((1+mthlyintfactor)^12-1,4);
float bb = ((1+(annintrate/2))^2)^(1/12)-1);
float cc = amortprd*12;
float dd = (principal * bb)/(1-(1+ bb)^(- cc));
float ee = ROUND(dd,2);
float ff = ROUND(dd,rndnearestcent,0);
}
}
}

[Dougsg38p]

Post the compiler message.

[Alex McQuaid]

Here is the compile list. Appreciate your assistance.....

Building LoanTable
C:\Research In Motion\BlackBerry JDE 4.5.0\bin\rapc.exe -quiet import="..\..\..\..\Research In Motion\BlackBerry JDE 4.5.0\lib\net_rim_api.jar" codename=LoanTable LoanTable.rapc warnkey=0x52424200;0x52525400;0x52435200 "C:\AFM BB APS\AFMTEST\test3\Test4\com\src\TableApp.java" "C:\AFM BB APS\AFMTEST\test3\Test4\com\src\TableScreen.java"
C:\AFM BB APS\AFMTEST\test3\Test4\com\src\TableScreen.java:6 5: ')' expected
rndnearestdollarField = new EditField(("Rounded to nearest dollar:$" + ff );
^
C:\AFM BB APS\AFMTEST\test3\Test4\com\src\TableScreen.java:7 0: class or interface expected
public void focusChanged(Field field, int eventType);
^
C:\AFM BB APS\AFMTEST\test3\Test4\com\src\TableScreen.java:7 1: class or interface expected
if (eventType == FOCUS_LOST) {
^
C:\AFM BB APS\AFMTEST\test3\Test4\com\src\TableScreen.java:7 4: class or interface expected
float bb = ((1+(annintrate/2))^2)^(1/12)-1);
^
C:\AFM BB APS\AFMTEST\test3\Test4\com\src\TableScreen.java:7 5: class or interface expected
float cc = amortprd*12;
^
C:\AFM BB APS\AFMTEST\test3\Test4\com\src\TableScreen.java:7 6: class or interface expected
float dd = (principal * bb)/(1-(1+ bb)^(- cc));
^
C:\AFM BB APS\AFMTEST\test3\Test4\com\src\TableScreen.java:7 7: class or interface expected
float ee = ROUND(dd,2);
^
C:\AFM BB APS\AFMTEST\test3\Test4\com\src\TableScreen.java:7 8: class or interface expected
float ff = ROUND(dd,rndnearestcent,0);
^
C:\AFM BB APS\AFMTEST\test3\Test4\com\src\TableScreen.java:7 9: class or interface expected
}
^
9 errors
Error!: Error: java compiler failed: javac -source 1.3 -target 1.1 -g -O -d C:\Users\ALEXMC~1\AppData\Local\Temp\rapc_6de6b9bf .dir -boot ...
Error while building project

[Dougsg38p]

First issue:

rndnearestdollarField = new EditField(("Rounded to nearest dollar:$" + ff );

should be

rndnearestdollarField = new EditField("Rounded to nearest dollar:$" + ff );

(you have an extra '(' in there)...

[Alex McQuaid]

First issue fixed....Thanks!

[romah]

import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.FieldChangeListener;
import net.rim.device.api.ui.FocusChangeListener;
import net.rim.device.api.ui.component.EditField;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.text.TextFilter;
import net.rim.device.api.ui.text.NumericTextFilter;
import net.rim.device.api.ui.container.MainScreen;

public class TableScreen extends MainScreen  implements FocusChangeListener {


 /// USER INPUT ///
  EditField custnbrField; /// 1234567890
  EditField principalField; /// $10,000.00
  EditField annintrateField; //// 10.00%
  EditField amortprdField; /// 3
  float aa=0,bb=0,cc=0,dd=0,ee=0,ff=0;
  
  /// CALCULATIONS ///
  EditField effannintrateField; // ROUND((1+mthlyintfactor)^12-1,4)....Result = 10.25%
  EditField mthlyintfactorField; // ((1+(annintrate/2))^2)^(1/12)-1).....Result = 0.008164846%
  EditField mthsamortField; // amortprd*12......Result = 36 mths
  EditField mthlypaymentField; // (principal * mthlyintfactor)/(1-(1+mthlyintfactor)^(-mthsamort)).....Result = $321.7234593
  EditField rndnearestcentField; // ROUND(mthlypayment,2).....Result = $321.72
  EditField rndnearestdollarField; // ROUND(rndnearestcent,0)..... Result = $322.00

        public TableScreen() {
        TextFilter numeric = new NumericTextFilter(NumericTextFilter.ALLOW_DECIMAL); 
            custnbrField = new EditField("Customer Number:  " , "");
            custnbrField.setFilter(TextFilter.get(TextFilter.NUMERIC)); // no decimal
            add(custnbrField);
         
            principalField = new EditField("Initial Principal: $ " , "");
            add(principalField);
         
            annintrateField = new EditField("Annual Interest Rate: % " , "");
            annintrateField.setFilter(numeric);
            add(annintrateField);
         
            amortprdField = new EditField("Amortization Period: (yrs) " , "");
            amortprdField.setFilter(TextFilter.get(TextFilter.NUMERIC)); // no decimal
            add(amortprdField);
         
            effannintrateField = new EditField("Effective Annual Interest Rate: %" + aa,"" );
            effannintrateField.setFilter(numeric);
            add(effannintrateField);
         
            mthlyintfactorField = new EditField("Monthly Interest Factor: " + bb,"" );
            add(mthlyintfactorField); 
         
            mthsamortField = new EditField("Months to Amortization: "+ cc,"" );
            add(mthsamortField); 
         
           
//// Monthly Payment to be displayed automatically after Monthly Interest Factor has been calculated
            mthlypaymentField = new EditField("Periodic Monthly Payment: $"+ dd,"" );
            add(mthlypaymentField); 
         
            rndnearestcentField = new EditField("Rounded to nearest cent: $" + ee ,"");
            add(rndnearestcentField); 
         
            rndnearestdollarField = new EditField("Rounded to nearest dollar:$" + ff ,"");
            add(rndnearestdollarField); 
 
      }

EditField has two arguments. See the definition: EditField(String label, String initialValue)
I didn't understand the calculation below but you should use getText() method of EditField to get the value and use Float.parseFloat() to change into float value.

Also you can use Math.round(), Math.ceil(), Math.floor(), Math.pow() method of Java for calculation. I didn't try these.

   
public void focusChanged(Field field, int eventType){
if (eventType == FOCUS_LOST) {
if (field == mthlypaymentField) {

aa = ROUND((1 + Float.parseFloat(mthlyintfactorField.getText()))^12-1,4);
bb = ((1+(Float.parseFloat(annintrateField.getText())/2))^2)^(1/12)-1);
cc = Float.parseFloat(annintrateField.getText())*12;
dd = (Float.parseFloat(principalField.getText()) * bb)/(1-(1+ bb)^(- cc));
ee = ROUND(dd,2);
ff = ROUND(dd,Float.parseFloat(rndnearestcentField.getText()),0); 
                    }
        }
    }
}

[romah]

There is one class net.rim.device.api.util.MathUtilities which provides some mathematical functions like MathUtilities.round(), MathUtilities.pow() etc. You can use those methods for your calculation.

Hope this will solve your problem.