I am making a object oriented program and hashing the list of make of an electronic and type to the JCombobox...i am getting this number Exception error...it will nice if you could tell why am i getting it eventhough i am doing the casting and everything. Try to help ASAP! thank you. Here's my code.
The following code is for buyPrinterDialog box.
public class BuyPrinters extends JDialog {
/**
*
*/
private static final long serialVersionUID = 1L;
private final JPanel contentPanel = new JPanel();
private JTextField textField;
String[] make = {"Lexmark", "HP" , "Apple" , "Brother" , "Canon", "Xerox"};
String [] type = {"Inkjet", "Laserjet"};
HashMap LexmarkPriceList = null;
HashMap HPPriceList = null;
HashMap ApplePriceList = null;
HashMap BrotherPriceList = null;
HashMap CanonPriceList = null;
HashMap XeroxPriceList = null;
/**
* Launch the application.
*/
MyFrame parent = null;
public static void main(String[] args) {
try {
BuyPrinters dialog = new BuyPrinters(null);
dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
dialog.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* Create the dialog.
*/
JComboBox makeComboBox = new JComboBox();
JComboBox typeComboBox = new JComboBox();
public BuyPrinters(MyFrame parent) {
this.parent = parent;
setIconImage(Toolkit.getDefaultToolkit().getImage("C:\\Users\\Gaurav sharma\\workspace\\Gaurav.Lovepreet.Harpreet.Java2.Project\\pics and icons\\printer_64.png"));
setTitle("BuyPrinters");
setBounds(100, 100, 525, 263);
getContentPane().setLayout(new BorderLayout());
contentPanel.setBackground(new Color(204, 204, 204));
contentPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
getContentPane().add(contentPanel, BorderLayout.CENTER);
contentPanel.setLayout(null);
{
JLabel lblMake = new JLabel("Make:");
lblMake.setFont(new Font("Tahoma", Font.BOLD, 12));
lblMake.setBounds(10, 11, 236, 24);
contentPanel.add(lblMake);
}
{
makeComboBox.setBounds(10, 46, 305, 20);
makeComboBox.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
updatePriceBox();
}
});
contentPanel.add(makeComboBox);
}
{
JLabel lblType = new JLabel("Type:");
lblType.setFont(new Font("Tahoma", Font.BOLD, 12));
lblType.setBounds(10, 77, 236, 24);
contentPanel.add(lblType);
}
{
typeComboBox.setBounds(10, 112, 305, 20);
typeComboBox.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
updatePriceBox();
}
});
contentPanel.add(typeComboBox);
}
{
textField = new JTextField();
textField.setEditable(false);
textField.setBounds(66, 155, 86, 20);
contentPanel.add(textField);
textField.setColumns(10);
}
{
JLabel lblPrice = new JLabel("Price:");
lblPrice.setFont(new Font("Tahoma", Font.BOLD, 12));
lblPrice.setBounds(10, 157, 46, 14);
contentPanel.add(lblPrice);
}
{
JPanel panel = new JPanel();
panel.setBackground(new Color(102, 255, 255));
panel.setBounds(348, 21, 151, 151);
contentPanel.add(panel);
panel.setLayout(null);
{
JButton btnNewButton = new JButton("");
btnNewButton.setIcon(new ImageIcon("C:\\Users\\Gaurav sharma\\workspace\\Gaurav.Lovepreet.Harpreet.Java2.Project\\pics and icons\\printer_64.png"));
btnNewButton.setBounds(0, 0, 151, 151);
panel.add(btnNewButton);
}
}
{
JPanel panel = new JPanel();
panel.setBackground(new Color(255, 153, 255));
panel.setBounds(0, 11, 338, 170);
contentPanel.add(panel);
}
JButton btnOk = new JButton("Ok");
btnOk.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
handleOk();
}
});
btnOk.setBounds(318, 191, 89, 23);
contentPanel.add(btnOk);
JButton btnCancel = new JButton("Cancel");
btnCancel.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
handleCancel();
}
});
btnCancel.setBounds(417, 191, 89, 23);
contentPanel.add(btnCancel);
{
JPanel buttonPane = new JPanel();
buttonPane.setBackground(new Color(102, 255, 255));
buttonPane.setLayout(new FlowLayout(FlowLayout.RIGHT));
//getContentPane().add(buttonPane, BorderLayout.SOUTH);
{
JButton okButton = new JButton("OK");
okButton.setActionCommand("OK");
buttonPane.add(okButton);
getRootPane().setDefaultButton(okButton);
}
{
JButton cancelButton = new JButton("Cancel");
cancelButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
handleCancel();
}
});
cancelButton.setActionCommand("Cancel");
buttonPane.add(cancelButton);
}
}
createMakePriceLists();
initializeMakeBox();
updatePriceBox();
}
private void handleCancel()
{
this.setVisible(false);
}
//Handling the Okay button.
private void handleOk()
{
this.setVisible(false);
Float price = Float.parseFloat(textField.getText());
Date manufactureDate = new Date();
int warrantyPeriodInYears = 3;
String make = (String) makeComboBox.getSelectedItem();
InkJet printer1 = new InkJet( price, manufactureDate, warrantyPeriodInYears, "type" ,make);
if (parent != null)
{
parent.updatePurchasedItemList(printer1);
}
}
//Creating Make pricelist which depends on the type they buy.
private void createMakePriceLists()
{
LexmarkPriceList = new HashMap();
LexmarkPriceList.put("Inkjet", 659f);
LexmarkPriceList.put("Laserjet", 799f);
HPPriceList = new HashMap();
HPPriceList.put("Inkjet", 299f);
HPPriceList.put("Laserjet", 359f);
ApplePriceList = new HashMap();
ApplePriceList.put("Inkjet", 999f);
ApplePriceList.put("Laserjet", 1089f);
BrotherPriceList = new HashMap();
BrotherPriceList.put("Inkjet", 99f);
BrotherPriceList.put("Laserjet", 159f);
CanonPriceList = new HashMap();
CanonPriceList.put("Inkjet", 299f);
CanonPriceList.put("Laserjet", 289f);
XeroxPriceList = new HashMap();
XeroxPriceList.put("Inkjet", 1299f);
XeroxPriceList.put("Laserjet", 1599f);
}
//Creating the type Price list which changes the price depending on whether the user buys laser or inkjet.
private void updatePriceBox()
{
String make = (String) makeComboBox.getSelectedItem();
System.out.println("update price box: selected make:"+make);
HashMap map = new HashMap() ;
if (make.equals("Lexmark"))
map = LexmarkPriceList;
if (make.equals("HP"))
map = HPPriceList;
if (make.equals("Xerox"))
map = XeroxPriceList;
if (make.equals("Brother"))
map = BrotherPriceList;
if (make.equals("Canon"))
map = CanonPriceList;
if (make.equals("Apple"))
map.equals(ApplePriceList);
makeComboBox.getSelectedItem();
Float price = (Float) map.get(make);
System.out.println(price);
textField.setText(""+ price);
}
//Initialize the Make box.
private void initializeMakeBox()
{
makeComboBox.removeAllItems();
for (String s : make) {
makeComboBox.addItem(s);
}
typeComboBox.removeAllItems();
for (String s : type) {
typeComboBox.addItem(s);
}
}
}
Number exception errors are typically execution time errors. You will need to check your data for any irregular data input.
The way to go about debugging it is to find out from the message on which source code line the error has occurred, and then trace back from there the probable variable that caused the error, and finally the data, or data conversion.
Even though you may have cast every numeric value, if the code is trying to parse a String or null into a number, the run-time error will occur.
Give it a trace and see if you can find the source of the error.
Also, typically, the kind of statements as:
Float price = Float.parseFloat(textField.getText());
would be best put inside a try-loop to catch any unexpected run-time errors.
thanks...yes i found the error. It was basically trying to parse a null which is a string. Yes i can try and catch the exception but haven't learned it but thanks for idea...i think i mite do that.
Good to hear!
If you have other questions, feel free!
Based on your code, it seems like you are getting a `NullPointerException` at the line `Float price = (Float) map.get(make);` in the `updatePriceBox()` method. This is likely because you haven't initialized the `ApplePriceList` correctly in the `createMakePriceLists()` method. In the line `map.equals(ApplePriceList);`, you should be using the assignment operator `=` instead of `equals()`.
Here's the corrected code:
```java
private void createMakePriceLists()
{
LexmarkPriceList = new HashMap();
LexmarkPriceList.put("Inkjet", 659f);
LexmarkPriceList.put("Laserjet", 799f);
HPPriceList = new HashMap();
HPPriceList.put("Inkjet", 299f);
HPPriceList.put("Laserjet", 359f);
ApplePriceList = new HashMap();
ApplePriceList.put("Inkjet", 999f);
ApplePriceList.put("Laserjet", 1089f);
BrotherPriceList = new HashMap();
BrotherPriceList.put("Inkjet", 99f);
BrotherPriceList.put("Laserjet", 159f);
CanonPriceList = new HashMap();
CanonPriceList.put("Inkjet", 299f);
CanonPriceList.put("Laserjet", 289f);
XeroxPriceList = new HashMap();
XeroxPriceList.put("Inkjet", 1299f);
XeroxPriceList.put("Laserjet", 1599f);
// corrected line
ApplePriceList = new HashMap();
ApplePriceList.put("Inkjet", 999f);
ApplePriceList.put("Laserjet", 1089f);
}
```
After making this correction, the `updatePriceBox()` method should work correctly and update the price in the text field based on the selected make in the combo box.