Having problems with do.while loops

Question

import javax.swing.*;
import java.text.DecimalFormat;
public class Assign32437 {
  public static void main(String[] args) {  // METHOD
   String strCost, strResVal, strUseLife, strDepre;
   double useLife = 0, deprec=0, Cost=0,resVal=0,accumulatedDepreciation = 0;
   double yearlyDepreciation = 0,Carryingvalue = 0;
   int repeat = 0, year = 0;
   DecimalFormat myFormat = new DecimalFormat("$0.00");
   JTextArea outputTextArea= new JTextArea();
     outputTextArea.append("\t\t Depreciation Schedule\n\n" + " End of year\t"
                           + "Cost\t" + "Yearly deprecation\t" +
                           "Accumulated Depreciation\t" + "Carrying value\n");
   do{   //ENTER COST OF ITEM
       strCost = JOptionPane.showInputDialog("Enter cost (>0):");
       Cost = Double.parseDouble(strCost);
    while (Cost < 0);
    do {       //ENTER ESTIMATED VALUE
       strResVal = JOptionPane.showInputDialog(
           "Enter residual value(>=0 and <cost:)");
       resVal = Double.parseDouble(strResVal);
    while (resVal < 0 || resVal > Cost);
    do {       //ENTER USEFUL LIFE
       strUseLife = JOptionPane.showInputDialog("Enter useful life(>0):");
       useLife = Double.parseDouble(strUseLife);
    while (useLife < 0);
    for (year = 0; year <= useLife; year++)
       deprec = (Cost - resVal) / (useLife);
       accumulatedDepreciation = (yearlyDepreciation * year); //CALCULATIONS
       Carryingvalue = (Cost - accumulatedDepreciation);
       outputTextArea.append(year + "\t" + Cost + "\t" + deprec + "\t" +
       accumulatedDepreciation + "\t" + Carryingvalue + "\n");
     JOptionPane.showMessageDialog(null, outputTextArea);
     repeat = JOptionPane.showConfirmDialog(null, "DO YOU WANT TO CONTINUE?\n",
                                            "Continue?",
                                            JOptionPane.YES_NO_OPTION);
     while(repeat==0);
   System.exit(0);
      }

Answer 1

no error msgs. im not asking someone to do it for me. just looking for some pointers...
when i run my code i am not being asked for more then one year ie: no loop is occuring. so i enter information and on my outputTextArea.append(year + "\t" + Cost + "\t" + deprec + "\t" +
       accumulatedDepreciation + "\t" + Carryingvalue + "\n"); displays one years totals like 30 times