Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException

Question

I am building an object-based program in java. It should calculate the salary and deduct some taxes. Taxes are to be checked using JCheckBox. The problem is when I click a checkbox, it shows the ff error:

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1842)
at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
at java.lang.Double.parseDouble(Double.java:538)
at WageCalcDriver.itemStateChanged(WageCalcDriver.java:140)
at javax.swing.AbstractButton.fireItemStateChanged(AbstractButton.java:2050)
at javax.swing.AbstractButton$Handler.itemStateChanged(AbstractButton.java:2353)
at javax.swing.DefaultButtonModel.fireItemStateChanged(DefaultButtonModel.java:455)
at javax.swing.JToggleButton$ToggleButtonModel.setSelected(JToggleButton.java:272)
at javax.swing.JToggleButton$ToggleButtonModel.setPressed(JToggleButton.java:289)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6527)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6292)
at java.awt.Container.processEvent(Container.java:2234)
at java.awt.Component.dispatchEventImpl(Component.java:4883)
at java.awt.Container.dispatchEventImpl(Container.java:2292)
at java.awt.Component.dispatchEvent(Component.java:4705)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
at java.awt.Container.dispatchEventImpl(Container.java:2278)
at java.awt.Window.dispatchEventImpl(Window.java:2739)
at java.awt.Component.dispatchEvent(Component.java:4705)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
at java.awt.EventQueue.access$400(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:697)
at java.awt.EventQueue$3.run(EventQueue.java:691)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:719)
at java.awt.EventQueue$4.run(EventQueue.java:717)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

Here is the program:

    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    import java.text.*;

    public class WageCalcDriver extends JFrame implements ActionListener, ItemListener
{
   private String workertype[] = {"Clerk", "Welder", "Purchaser", "Sales Manager"};
   private JComboBox combo = new JComboBox(workertype);
   private JLabel comboLabel = new JLabel("Type of Work: ");

   private JLabel wageLabel = new JLabel();
   private JTextField wageTextField = new JTextField();

   private JLabel hourLabel = new JLabel();
   private JTextField hourTextField = new JTextField();

   private JLabel gwageLabel = new JLabel();
   private JTextField gwageTextField = new JTextField();

   private JLabel deductions = new JLabel("Deductions: ");
   private JCheckBox sss = new JCheckBox("SSS");
   private JCheckBox philhealth = new JCheckBox("PHILHEALTH");
   private JCheckBox pagibig = new JCheckBox("PAG-IBIG");

   private JLabel netLabel = new JLabel("Net Income: ");
       private JTextField netTextField = new JTextField("");

        JLabel detailsLabel = new JLabel ("Deduction Info:");
        String names[] = {"PAG-IBIG", "SSS", "PHILHEALTH"};
        JComboBox detailCombo = new JComboBox(names);
        JTextField detail = new JTextField(5);

       private JButton calculateJButton = new JButton("CALCULATE");

   public WageCalcDriver()
   {
      Container c = getContentPane();
      c.setLayout( null ); 

      c.add(comboLabel);
      c.add(combo); 
      c.add( wageLabel );
      c.add( wageTextField );
      c.add( hourLabel );
      c.add( hourTextField );
      c.add( gwageLabel );
      c.add( gwageTextField );
      c.add( deductions );
      c.add( sss );
      c.add( philhealth );
      c.add( pagibig );
      c.add( netLabel );
      c.add( netTextField );
      c.add( calculateJButton );
      c.add( detailsLabel );
      c.add( detailCombo );
      c.add( detail );

      comboLabel.setBounds(16,20,100,21);       combo.setBounds(120,20,100,20);
      wageLabel.setBounds( 16, 50, 100, 21 );   wageTextField.setBounds( 120, 50, 100, 21 );
      hourLabel.setBounds( 16, 80, 100, 21 );   hourTextField.setBounds( 120, 80, 100, 21 );
      gwageLabel.setBounds( 16, 110, 100, 21 ); gwageTextField.setBounds( 120, 110, 100, 21 );

      deductions.setBounds(16,140,100,21);      sss.setBounds(120,140,100,21);
                                                philhealth.setBounds(120,170,100,21);
                                                pagibig.setBounds(120,200,100,21);

      netLabel.setBounds(16,230,100,21);        netTextField.setBounds(120,230,100,21);
      detailsLabel.setBounds(16,260,100,21);    detailCombo.setBounds(120,260,100,21);
      detail.setBounds(16,290,200,100);

      calculateJButton.setBounds( 50, 600, 120, 24 );

      gwageLabel.setText( "Gross wages:" );
      wageLabel.setText( "Hourly wage:" );
      hourLabel.setText( "Hours worked:" );


      wageTextField.setHorizontalAlignment(JTextField.RIGHT );
      hourTextField.setHorizontalAlignment(JTextField.RIGHT );
      gwageTextField.setHorizontalAlignment(JTextField.RIGHT );

      gwageTextField.setEditable( false );
      netTextField.setEditable( false );

      combo.addItemListener(this);
      detailCombo.addItemListener(this);
      calculateJButton.addActionListener(this);        
      sss.addItemListener(this);
      philhealth.addItemListener(this);
      pagibig.addItemListener(this);

      setTitle( "Wage Calculator" ); 
      setSize( 245, 700 );           
      setVisible( true );            

    //      netTextField.setText(netinc()); 

       } //constructor end

       public void actionPerformed(ActionEvent e)
   {
        if(e.getSource() == calculateJButton)
    {
      double hourlyWage = Double.parseDouble( wageTextField.getText() );

      double hoursWorked = Double.parseDouble( hourTextField.getText() );

      WageCalcObj object = new WageCalcObj(hoursWorked, hourlyWage);

      gwageTextField.setText(object.calculatePay());
    }       
   }

   public void itemStateChanged(ItemEvent e)
   {
    if(e.getSource() == sss)
    {
        if (e.getStateChange() == ItemEvent.SELECTED)
        {
     double hourlyWage = Double.parseDouble( wageTextField.getText() );
     double hoursWorked = Double.parseDouble( hourTextField.getText() );
     WageCalcObj object_sss = new WageCalcObj(hoursWorked, hourlyWage);
     netTextField.setText(object_sss.deduct_sss());
        }       
    }

    if(e.getSource() == pagibig)
    {
     double hourlyWage = Double.parseDouble( wageTextField.getText() );
     double hoursWorked = Double.parseDouble( hourTextField.getText() );
     WageCalcObj object_pagibig = new WageCalcObj(hoursWorked, hourlyWage);
     netTextField.setText(object_pagibig.deduct_pagibig()); 
    }

    if(e.getSource() == philhealth)
    {
     double hourlyWage = Double.parseDouble( wageTextField.getText() );
     double hoursWorked = Double.parseDouble( hourTextField.getText() );
     WageCalcObj object_philhealth = new WageCalcObj(hoursWorked, hourlyWage);
     netTextField.setText(object_philhealth.deduct_philhealth());   
    }



   }

   public static void main( String[] args )
   {
      WageCalcDriver app = new WageCalcDriver();
      app.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );

   } 

} 

What should i do to correct this? Thanks in advance :)

Answer 1

It seems that

 double hourlyWage = Double.parseDouble( wageTextField.getText() );

 double hoursWorked = Double.parseDouble( hourTextField.getText() );

wageTextField or hourTextField is empty string when click button. Check it.

SOLUTION

When click on calculate button is performed (actionPerformed method) you should check if wageTextField and hourTextField are not empty. If one of them is empty, two lines above shouldn't be executed.

Answer 2

You always have to validate user input before using it. Or catch the NumberFormatException and translate it to a user friendly validation error on the user interface.