My program won't run properly

Question

Here's my JFrame apps, it's creating an array of 10 inner Car object and then proceeds to define the first two objects. Then through the buttons, Display Next, you're supposed to display the values in the object, starting with the first. I got the Clear button and the Display Button working, but it seems that the Add, Search and Change buttons won't work properly. Help me please!
import java.lang.String.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.DecimalFormat;
import java.util.*;
public class CarRental extends JFrame implements ActionListener
private Car cars[] = new Car[10];
private char ct;
private Date d;
private double f, fee;
private int addCount, carCount = 0, displayCount = -1;
private int searchCount = 0, yMade, yRented, mRented, dRented;
private JButton bDisplayNext, bClear, bSearch;
private JButton bAdd, bChange;
private JLabel lLicense, lYear, lCategory;
private JLabel lFee, lDateRented, lMessage;
private JPanel infoPanel, buttonPanel, messagePanel;
private JPanel panel1, panel2, panel3, panel4, panel5;
private JRadioButton rbSubcompact, rbIntermediate, rbLuxury;
private JTextField tLicense, tYear;
private JTextField tFee, tDateRented;
private String licsNum, feeVal, yVal, mVal, dVal;
private String dateVal, rf, searchString;
DecimalFormat twoDigits = new DecimalFormat("0.00");
DecimalFormat twoNumber = new DecimalFormat("00");
DecimalFormat fourNumber = new DecimalFormat("0000");
public CarRental()
super("Madterp's Rental Cars");
cars[0] = new Car("ABC111",1999,'S',100,0,0,0);
cars[1] = new Car("DEF222",2002,'I',160,2002,2,2);
carCount += 2;
infoPanel = new JPanel();
infoPanel.setLayout(new GridLayout(5,1));
panel1 = new JPanel();
panel1.setLayout(new FlowLayout());
lLicense = new JLabel("License Number: ");
tLicense = new JTextField(30);
panel1.add(lLicense);
panel1.add(tLicense);
panel2 = new JPanel();
panel2.setLayout(new FlowLayout());
lYear = new JLabel("Year Made: ");
tYear = new JTextField(30);
panel2.add(lYear);
panel2.add(tYear);
panel3 = new JPanel();
panel3.setLayout(new FlowLayout());
lCategory = new JLabel("Category: ");
rbSubcompact = new JRadioButton("S", true);
rbIntermediate = new JRadioButton("I",false);
rbLuxury = new JRadioButton("L",false);
panel3.add(lCategory);
panel3.add(rbSubcompact);
panel3.add(rbIntermediate);
panel3.add(rbLuxury);
panel4 = new JPanel();
panel4.setLayout(new FlowLayout());
lFee = new JLabel("Daily Rental Fee: ");
tFee = new JTextField(30);
panel4.add(lFee);
panel4.add(tFee);
panel5 = new JPanel();
panel5.setLayout(new FlowLayout());
lDateRented = new JLabel("Date Rented: ");
tDateRented = new JTextField(30);
panel5.add(lDateRented);
panel5.add(tDateRented);
infoPanel.add(panel1);
infoPanel.add(panel2);
infoPanel.add(panel3);
infoPanel.add(panel4);
infoPanel.add(panel5);
buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(1,5,3,3));
bDisplayNext = new JButton("Display Next");
bDisplayNext.addActionListener(this);
buttonPanel.add(bDisplayNext);
bClear = new JButton("Clear");
bClear.addActionListener(this);
buttonPanel.add(bClear);
bSearch = new JButton("Search");
bSearch.addActionListener(this);
buttonPanel.add(bSearch);
bAdd = new JButton("Add");
bAdd.addActionListener(this);
buttonPanel.add(bAdd);
bChange = new JButton("Change");
bChange.addActionListener(this);
buttonPanel.add(bChange);
messagePanel = new JPanel();
messagePanel.setLayout(new FlowLayout());
lMessage = new JLabel("");
messagePanel.add(lMessage);
Container c = getContentPane();
c.add(infoPanel, BorderLayout.NORTH);
c.add(buttonPanel, BorderLayout.CENTER);
c.add(messagePanel, BorderLayout.SOUTH);
setSize(700,500);
show();
public static void main(String args[])
CarRental app = new CarRental();
app.addWindowListener
new WindowAdapter()
public void windowClosing(WindowEvent e)
System.exit(0);
public void actionPerformed(ActionEvent e)
if (e.getSource() == bDisplayNext)
if (displayCount > carCount || displayCount > 10)
lMessage.setText("No More Cars!");
else
displayCount += 1;
licsNum = cars[displayCount].getLicenseNum();
yVal = fourNumber.format(cars[displayCount].getYearMade());
ct = cars[displayCount].getCategory();
rf = twoDigits.format(cars[displayCount].getFee());
d = cars[displayCount].getRentedDate();
tLicense.setText(licsNum);
tYear.setText(yVal);
tFee.setText(rf);
tDateRented.setText(d.toString());
if (ct == 'S' || ct == 's')
rbSubcompact.setSelected(true);
rbIntermediate.setSelected(false);
rbLuxury.setSelected(false);
else if (ct == 'I' || ct == 'i')
rbSubcompact.setSelected(false);
rbSubcompact.setSelected(true);
rbSubcompact.setSelected(false);
else if (ct == 'L' || ct == 'l')
rbSubcompact.setSelected(false);
rbSubcompact.setSelected(false);
rbSubcompact.setSelected(true);
else if (e.getSource() == bSearch)
int found = 0, noOfFound = 0;
DecimalFormat fourNumber = new DecimalFormat("0000");
DecimalFormat twoDigits = new DecimalFormat("0.00");
searchString = tLicense.getText();
searchCount = 0;
if (searchString != "")
while (searchCount < carCount && found != 1)
licsNum = cars[searchCount].getLicenseNum();
if (searchString == licsNum)
yVal = fourNumber.format(cars[searchCount].getYearMade());
ct = cars[searchCount].getCategory();
     rf = twoDigits.format(cars[searchCount].getFee());
     d = cars[searchCount].getRentedDate();
noOfFound++;
found = 1;
else
found = 0;
searchCount++;
if (noOfFound > 0)
tLicense.setText(licsNum);
tYear.setText(yVal);
tFee.setText(rf);
tDateRented.setText(d.toString());
lMessage.setText("Search Found!");
else
lMessage.setText("Search Not Found!");
else
lMessage.setText("Search Not Valid!");
else if (e.getSource() == bAdd)
int count = 0;
int foundEmpty = 0;
while (count < 10 && foundEmpty != 1)
String s = cars[count].getLicenseNum();
if (s != "")
count++;
foundEmpty = 0;
else
foundEmpty = 1;
if ( count < 10 )
licsNum = tLicense.getText();
feeVal = tFee.getText();
yVal = tYear.getText();
dateVal = tDateRented.getText();
if (feeVal != "")
fee = Double.parseDouble(feeVal);
else
fee = 0;
if (yVal != "")
yMade = Integer.parseInt(yVal);
else
yMade = 0;
if (rbSubcompact.isSelected())
ct = 'S';
if (rbIntermediate.isSelected())
ct = 'I';
if (rbLuxury.isSelected())
ct = 'L';
if (dateVal != "")
int s1 = dateVal.indexOf("/");
int s2 = dateVal.indexOf("/", s1+1);
int i = 0;
while (i < s1)
yVal += dateVal.charAt(i);
i++;
i = s1 + 1;
while (i < s2)
mVal += dateVal.charAt(i);
i++;
i = s2 + 1;
while (i < dateVal.length())
dVal += dateVal.charAt(i);
i++;
yRented = Integer.parseInt(yVal);
mRented = Integer.parseInt(mVal);
dRented = Integer.parseInt(dVal);
else
yRented = 0;
mRented = 0;
dRented = 0;
cars[count] = new Car(licsNum, yMade, ct, fee, yRented, mRented, dRented);
else
lMessage.setText("No More Room To Add A New Car!");
if (e.getSource() == bChange)
licsNum = tLicense.getText();
feeVal = tFee.getText();
yVal = tYear.getText();
dateVal = tDateRented.getText();
if (feeVal != "")
fee = Double.parseDouble(feeVal);
else
fee = 0;
if (yVal != "")
yMade = Integer.parseInt(yVal);
else
yMade = 0;
if (rbSubcompact.isSelected())
ct = 'S';
if (rbIntermediate.isSelected())
ct = 'I';
if (rbLuxury.isSelected())
ct = 'L';
if (dateVal != "")
int s1 = dateVal.indexOf("/");
int s2 = dateVal.indexOf("/", s1+1);
int i = 0;
while (i < s1)
yVal += dateVal.charAt(i);
i++;
i = s1 + 1;
while (i < s2)
mVal += dateVal.charAt(i);
i++;
i = s2 + 1;
while (i < dateVal.length())
dVal += dateVal.charAt(i);
i++;
yRented = Integer.parseInt(yVal);
mRented = Integer.parseInt(mVal);
dRented = Integer.parseInt(dVal);
else
yRented = 0;
mRented = 0;
dRented = 0;
if (displayCount <= carCount)
cars[displayCount].setLicenseNum(licsNum);
cars[displayCount].setYearMade(yMade);
cars[displayCount].setCategory(ct);
cars[displayCount].setFee(fee);
cars[displayCount].setRentedDate(yRented, mRented, dRented);
else
lMessage.setText("No car to change!");
else if (e.getSource() == bClear)
displayCount = -1;
tLicense.setText("");
tYear.setText("");
tFee.setText("");
tDateRented.setText("");
lMessage.setText("");
rbSubcompact.setSelected(true);
rbIntermediate.setSelected(false);
rbLuxury.setSelected(false);
public class Car
private String licenseNum;
private int yearMade;
private char category;
private double fee;
private Date rentedDate;
public Car(String l, int yM, char c, double f, int yR, int mR, int dR)
setLicenseNum(l);
setYearMade(yM);
setCategory(c);
setFee(f);
setRentedDate(yR,mR,dR);
public void setLicenseNum(String l)
licenseNum = l;
public void setYearMade(int yM)
yearMade = yM;
public void setCategory(char c)
category = c;
public void setFee(double f)
fee = f;
public void setRentedDate(int yR, int mR, int dR)
rentedDate = new Date(yR,mR,dR);
public String getLicenseNum()
return licenseNum;
public int getYearMade()
return yearMade;
public char getCategory()
return category;
public double getFee()
return fee;
public Date getRentedDate()
return rentedDate;
public String toString()
DecimalFormat twoDigits = new DecimalFormat("0.00");
return licenseNum + " " + yearMade + " " + category + " " + twoDigits.format( fee ) + " " + rentedDate.toString();
public class Date
private int month;
private int day;
private int year;
public Date( int yr, int mn, int dy )
if ( mn > 0 && mn <= 12 )
month = mn;
else
month = 0;
year = yr;
day = checkDay( dy );
private int checkDay( int testDay )
int daysPerMonth[] = { 0, 31, 28, 31, 30,
31, 30, 31, 31, 30,
31, 30, 31 };
if ( testDay > 0 && testDay <= daysPerMonth[ month ] )
return testDay;
if ( month == 2 && testDay == 29 &&
( year % 400 == 0 || ( year % 4 == 0 && year % 100 != 0 ) ) )
return testDay;
return 0;
public String toString()
return fourNumber.format(year) + "/" + twoNumber.format(month) + "/" + twoNumber.format(day);
I have tried to put the actionPerformed sections into different sections. For each if or else if, I've tried to put them into another function. But still it didn't work. Can you tell me what's wrong with my logic and can you fix it? Thanks!

Answer 1

Hi there,
Your code as is is giving exceptions on hitting displaynext button after the first 2 cars are displayed.
Pl find below some changes to yuor code, now displaynest, search and clear buttons work fine.
In order to make the Change and Add buttons work, what you need to do is, instead of hardcoding the Car values in an array as you have done, store these values in a file or database table and only then, you will bw able to add or change these values. Cheers.
import java.lang.String.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.DecimalFormat;
import java.util.*;
public class CarRental extends JFrame implements ActionListener
          private Car cars[] = new Car[10];
          private char ct;
          private Date d;
          private double f, fee;
          private int addCount, carCount = 0, displayCount = 0;
          private int searchCount = 0, yMade, yRented, mRented, dRented;
          private JButton bDisplayNext, bClear, bSearch,bAdd, bChange;
          private JLabel lLicense, lYear, lCategory, lFee, lDateRented, lMessage;
          private JPanel infoPanel, buttonPanel, messagePanel, panel1, panel2, panel3, panel4, panel5;
          private JRadioButton rbSubcompact, rbIntermediate, rbLuxury;
          private JTextField tLicense, tYear, tFee, tDateRented;
          private String licsNum, feeVal, yVal, mVal, dVal, dateVal, rf, searchString;
          DecimalFormat twoDigits = new DecimalFormat("0.00");
          DecimalFormat twoNumber = new DecimalFormat("00");
          DecimalFormat fourNumber = new DecimalFormat("0000");
          public CarRental()
                    super("Madterp's Rental Cars");
                    cars[0] = new Car("ABC111",1999,'S',100,0,0,0);
                    cars[1] = new Car("DEF222",2002,'I',160,2002,2,2);
                    cars[2] = new Car("GHJ333",2003,'I',160,2002,2,2);
                    cars[3] = new Car("KLM444",2004,'I',160,2002,2,2);
                    cars[4] = new Car("NOP555",2005,'I',160,2002,2,2);
                    cars[5] = new Car("QRS666",2006,'I',160,2002,2,2);
                    cars[6] = new Car("TUV777",2007,'I',160,2002,2,2);
                    cars[7] = new Car("XYZ888",2002,'I',160,2002,2,2);
                    cars[8] = new Car("AAA888",2002,'I',160,2002,2,2);
                    cars[9] = new Car("BBB222",2002,'I',160,2002,2,2);
                    carCount += 10;
                    infoPanel = new JPanel();
                    infoPanel.setLayout(new GridLayout(5,1));
                    panel1 = new JPanel();
                    lLicense = new JLabel("License Number: ");
                    tLicense = new JTextField(30);
                    panel1.add(lLicense);
                    panel1.add(tLicense);
                    panel2 = new JPanel();
                    lYear = new JLabel("Year Made: ");
                    tYear = new JTextField(30);
                    panel2.add(lYear);
                    panel2.add(tYear);
                    panel3 = new JPanel();
                    lCategory = new JLabel("Category: ");
                    rbSubcompact = new JRadioButton("S", true);
                    rbIntermediate = new JRadioButton("I",false);
                    rbLuxury = new JRadioButton("L",false);
                    panel3.add(lCategory);
                    panel3.add(rbSubcompact);
                    panel3.add(rbIntermediate);
                    panel3.add(rbLuxury);
                    panel4 = new JPanel();
                    lFee = new JLabel("Daily Rental Fee: ");
                    tFee = new JTextField(30);
                    panel4.add(lFee);
                    panel4.add(tFee);
                    panel5 = new JPanel();
                    lDateRented = new JLabel("Date Rented: ");
                    tDateRented = new JTextField(30);
                    panel5.add(lDateRented);
                    panel5.add(tDateRented);
                    infoPanel.add(panel1);
                    infoPanel.add(panel2);
                    infoPanel.add(panel3);
                    infoPanel.add(panel4);
                    infoPanel.add(panel5);
                    buttonPanel = new JPanel();
                    buttonPanel.setLayout(new GridLayout(1,5,3,3));
                    bDisplayNext = new JButton("Display Next");
                    bDisplayNext.addActionListener(this);
                    buttonPanel.add(bDisplayNext);
                    bClear = new JButton("Clear");
                    bClear.addActionListener(this);
                    buttonPanel.add(bClear);
                    bSearch = new JButton("Search");
                    bSearch.addActionListener(this);
                    buttonPanel.add(bSearch);
                    bAdd = new JButton("Add");
                    bAdd.addActionListener(this);
                    buttonPanel.add(bAdd);
                    bChange = new JButton("Change");
                    bChange.addActionListener(this);
                    buttonPanel.add(bChange);
                    messagePanel = new JPanel();
                    messagePanel.setLayout(new FlowLayout());
                    lMessage = new JLabel("");
                    messagePanel.add(lMessage);
                    Container c = getContentPane();
                    c.add(infoPanel, BorderLayout.NORTH);
                    c.add(buttonPanel, BorderLayout.CENTER);
                    c.add(messagePanel, BorderLayout.SOUTH);
                    setSize(700,500);
                    show();
          public static void main(String args[])
               CarRental app = new CarRental();
               app.addWindowListener
                    (new WindowAdapter()
                                   public void windowClosing(WindowEvent e)
                                        System.exit(0);
     public void actionPerformed(ActionEvent e)
          if (e.getSource() == bDisplayNext)
                    if ( displayCount > 9)
                         lMessage.setText("No More Cars!");
                    else
                              licsNum = cars[displayCount].getLicenseNum();
                              yVal = fourNumber.format(cars[displayCount].getYearMade());
                              ct = cars[displayCount].getCategory();
                              rf = twoDigits.format(cars[displayCount].getFee());
                              d = cars[displayCount].getRentedDate();
                              tLicense.setText(licsNum);
                              tYear.setText(yVal);
                              tFee.setText(rf);
                              tDateRented.setText(d.toString());
                              if (ct == 'S' || ct == 's')
                                        rbSubcompact.setSelected(true);
                                        rbIntermediate.setSelected(false);
                                        rbLuxury.setSelected(false);
                              else if (ct == 'I' || ct == 'i')
                                        rbSubcompact.setSelected(false);
                                        rbSubcompact.setSelected(true);
                                        rbSubcompact.setSelected(false);
                              else if (ct == 'L' || ct == 'l')
                                        rbSubcompact.setSelected(false);
                                        rbSubcompact.setSelected(false);
                                        rbSubcompact.setSelected(true);
                              displayCount += 1;
          else if (e.getSource() == bSearch)
                    int found = 0, noOfFound = 0;
                    DecimalFormat fourNumber = new DecimalFormat("0000");
                    DecimalFormat twoDigits = new DecimalFormat("0.00");
                    searchString = tLicense.getText();
                    searchCount = 0;
                    if (searchString != "")
                              while (searchCount < carCount && found != 1)
                                   licsNum = cars[searchCount].getLicenseNum();
                                        if (searchString.equals(licsNum)) {
                                                  yVal = fourNumber.format(cars[searchCount].getYearMade());
                                                  ct = cars[searchCount].getCategory();
                                                  rf = twoDigits.format(cars[searchCount].getFee());
                                                  d = cars[searchCount].getRentedDate();
                                                  noOfFound++;
                                                  found = 1;
                                        else {
                                             found = 0;
                                   searchCount++;
                                        if (noOfFound > 0) {
                                                  tLicense.setText(licsNum);
                                                  tYear.setText(yVal);
                                                  tFee.setText(rf);
                                                  tDateRented.setText(d.toString());
                                                  lMessage.setText("Search Found!");
                                        else     {
                                             lMessage.setText("Search Not Found!");
                         else     {
                              lMessage.setText("Search Not Valid!");
               else if (e.getSource() == bAdd)
                              int count = 0;
                              int foundEmpty = 0;
                              while (count < 10 && foundEmpty != 1)
                                   String s = cars[count].getLicenseNum();
                                        if (s != "")
                                                  count++;
                                                  foundEmpty = 0;
                                        else
                                             foundEmpty = 1;
                              if ( count < 10 )
                                        licsNum = tLicense.getText();
                                        feeVal = tFee.getText();
                                        yVal = tYear.getText();
                                        dateVal = tDateRented.getText();
                                        if (feeVal != "")     {
                                             fee = Double.parseDouble(feeVal);
                                        else {
                                             fee = 0;
                                        if (yVal != "")     {
                                             yMade = Integer.parseInt(yVal);
                                        else {
                                             yMade = 0;
                                        if (rbSubcompact.isSelected()) {
                                             ct = 'S';
                                        if (rbIntermediate.isSelected()) {
                                             ct = 'I';
                                        if (rbLuxury.isSelected()) {
                                             ct = 'L';
                                        if (dateVal != "") {
                                                  int s1 = dateVal.indexOf("/");
                                                  int s2 = dateVal.indexOf("/", s1+1);
                                                  int i = 0;
                                                  while (i < s1) {
                                                            yVal += dateVal.charAt(i);
                                                            i++;
                                                  i = s1 + 1;
                                                  while (i < s2) {
                                                            mVal += dateVal.charAt(i);
                                                            i++;
                                                  i = s2 + 1;
                                                  while (i < dateVal.length()) {
                                                            dVal += dateVal.charAt(i);
                                                            i++;
                                                  yRented = Integer.parseInt(yVal);
                                                  mRented = Integer.parseInt(mVal);
                                                  dRented = Integer.parseInt(dVal);
                                             else {
                                                            yRented = 0;
                                                            mRented = 0;
                                                            dRented = 0;
                                             cars[count] = new Car(licsNum, yMade, ct, fee, yRented, mRented, dRented);
                                   else {
                                        lMessage.setText("No More Room To Add A New Car!");
                    if (e.getSource() == bChange)
                              searchString = tLicense.getText();
                              feeVal = tFee.getText();
                              yVal = tYear.getText();
                              dateVal = tDateRented.getText();
                              int searchCount = 0;
                              if (searchString != "")
                                        while (searchCount < carCount )
                                             licsNum = cars[searchCount].getLicenseNum();
                                                  if (searchString.equals(licsNum)) {
                                                            displayCount = searchCount;
                              if (feeVal != "")                              {
                                   fee = Double.parseDouble(feeVal);
                              else {
                                   fee = 0;
                              if (yVal != "")     {
                                   yMade = Integer.parseInt(yVal);
                              else {
                                   yMade = 0;
                              if (rbSubcompact.isSelected()){
                                   ct = 'S';
                              else if (rbIntermediate.isSelected()){
                                   ct = 'I';
                              else if (rbLuxury.isSelected()){
                                   ct = 'L';
                              if (dateVal != "")
                                        int s1 = dateVal.indexOf("/");
                                        int s2 = dateVal.indexOf("/", s1+1);
                                        int i = 0;
                                        while (i < s1){
                                                  yVal += dateVal.charAt(i);
                                                  i++;
                                        i = s1 + 1;
                                        while (i < s2){
                                                  mVal += dateVal.charAt(i);
                                                  i++;
                                        i = s2 + 1;
                                        while (i < dateVal.length()){
                                                  dVal += dateVal.charAt(i);
                                                  i++;
                                        yRented = Integer.parseInt(yVal);
                                        mRented = Integer.parseInt(mVal);
                                        dRented = Integer.parseInt(dVal);
                              else
                                        yRented = 0;
                                        mRented = 0;
                                        dRented = 0;
                              if (displayCount <= carCount)
                                        cars[displayCount].setLicenseNum(licsNum);
                                        cars[displayCount].setYearMade(yMade);
                                        cars[displayCount].setCategory(ct);
                                        cars[displayCount].setFee(fee);
                                        cars[displayCount].setRentedDate(yRented, mRented, dRented);
                              else
                                   lMessage.setText("No car to change!");
                    else if (e.getSource() == bClear)
                              displayCount = 0;
                              tLicense.setText("");
                              tYear.setText("");
                              tFee.setText("");
                              tDateRented.setText("");
                              lMessage.setText("");
                              rbSubcompact.setSelected(true);
                              rbIntermediate.setSelected(false);
                              rbLuxury.setSelected(false);
          public class Car
                    private String licenseNum;
                    private int yearMade;
                    private char category;
                    private double fee;
                    private Date rentedDate;
                    public Car(String l, int yM, char c, double f, int yR, int mR, int dR){
                              setLicenseNum(l);
                              setYearMade(yM);
                              setCategory(c);
                              setFee(f);
                              setRentedDate(yR,mR,dR);
                    public void setLicenseNum(String l){
                         licenseNum = l;
                    public void setYearMade(int yM){
                         yearMade = yM;
                    public void setCategory(char c){
                         category = c;
                    public void setFee(double f){
                         fee = f;
                    public void setRentedDate(int yR, int mR, int dR){
                         rentedDate = new Date(yR,mR,dR);
                    public String getLicenseNum(){
                         return licenseNum;
                    public int getYearMade(){
                         return yearMade;
                    public char getCategory(){
                         return category;
                    public double getFee(){
                         return fee;
                    public Date getRentedDate(){
                         return rentedDate;
                    public String toString() {
                              DecimalFormat twoDigits = new DecimalFormat("0.00");
                              return licenseNum + " " + yearMade + " " + category + " " + twoDigits.format( fee ) + " " + rentedDate.toString();
          public class Date
                    private int month;
                    private int day;
                    private int year;
                    public Date( int yr, int mn, int dy ) {
                              if ( mn > 0 && mn <= 12 )     {
                                   month = mn;
                              else           {
                                   month = 0;
                              year = yr;
                              day = checkDay( dy );
                    private int checkDay( int testDay ) {
                         int daysPerMonth[] = { 0, 31, 28, 31, 30,     31, 30, 31, 31, 30,     31, 30, 31 };
                              if ( testDay > 0 && testDay <= daysPerMonth[ month ] ) {
                                   return testDay;
                              if ( month == 2 && testDay == 29 && ( year % 400 == 0 || ( year % 4 == 0 && year % 100 != 0 ) ) ) {
                                   return testDay;
                         return 0;
                    public String toString()
                         return fourNumber.format(year) + "/" + twoNumber.format(month) + "/" + twoNumber.format(day);