There are no errors when I compile the program, but when I run it and use the "Enter" or "Clear" buttons, they do not work.
----jGRASP exec: java IncomeTax
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at IncomeTax.enterJButtonActionPerformed(IncomeTax.java:182)
at IncomeTax$1.actionPerformed(IncomeTax.java:125)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6525)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6290)
at java.awt.Container.processEvent(Container.java:2234)
at java.awt.Component.dispatchEventImpl(Component.java:4881)
at java.awt.Container.dispatchEventImpl(Container.java:2292)
at java.awt.Component.dispatchEvent(Component.java:4703)
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:4703)
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)
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.*; // import formatting
public class IncomeTax extends JFrame
{
// declarations
Color black = new Color(0, 0, 0);
Color white = new Color(255, 255, 255);
DecimalFormat currency; // declare currency
JLabel grossIncomeJLabel;
JTextField grossIncomeJTextField;
JLabel taxJLabel;
JTextField taxJTextField;
JLabel netIncomeJLabel;
JTextField netIncomeJTextField;
JButton enterJButton;
JButton clearJButton;
JButton closeJButton;
double grossIncome;
double tax;
double netIncome;
double taxRate;
public IncomeTax()
{
createUserInterface();
}
public void createUserInterface()
{
Container contentPane = getContentPane();
contentPane.setBackground(white);
contentPane.setLayout(null);
//initialize components
JLabel grossIncomeJLabel;
grossIncomeJLabel = new JLabel();
grossIncomeJLabel.setBounds(50, 20, 150, 20);
grossIncomeJLabel.setFont(new Font("Default", Font.PLAIN, 12));
grossIncomeJLabel.setText("Enter Gross Income:");
grossIncomeJLabel.setForeground(black);
grossIncomeJLabel.setHorizontalAlignment(JLabel.LEFT);
contentPane.add(grossIncomeJLabel);
JTextField grossIncomeJTextField;
grossIncomeJTextField = new JTextField();
grossIncomeJTextField.setBounds(200, 20, 100, 20);
grossIncomeJTextField.setFont(new Font("Default", Font.PLAIN, 12));
grossIncomeJTextField.setHorizontalAlignment(JTextField.CENTER);
grossIncomeJTextField.setForeground(black);
grossIncomeJTextField.setBackground(white);
grossIncomeJTextField.setEditable(true);
contentPane.add(grossIncomeJTextField);
JLabel taxJLabel;
taxJLabel = new JLabel();
taxJLabel.setBounds(50, 110, 150, 20);
taxJLabel.setFont(new Font("Default", Font.PLAIN, 12));
taxJLabel.setText("Income Tax:");
taxJLabel.setForeground(black);
taxJLabel.setHorizontalAlignment(JLabel.LEFT);
contentPane.add(taxJLabel);
JTextField taxJTextField;
taxJTextField = new JTextField();
taxJTextField.setBounds(200, 110, 100, 20);
taxJTextField.setFont(new Font("Default", Font.PLAIN, 12));
taxJTextField.setHorizontalAlignment(JTextField.CENTER);
taxJTextField.setForeground(black);
taxJTextField.setBackground(white);
taxJTextField.setEditable(false);
contentPane.add(taxJTextField);
JLabel netIncomeJLabel;
netIncomeJLabel = new JLabel();
netIncomeJLabel.setBounds(50, 140, 150, 20);
netIncomeJLabel.setFont(new Font("Default", Font.PLAIN, 12));
netIncomeJLabel.setText("Net Income:");
netIncomeJLabel.setForeground(black);
netIncomeJLabel.setHorizontalAlignment(JLabel.LEFT);
contentPane.add(netIncomeJLabel);
JTextField netIncomeJTextField;
netIncomeJTextField = new JTextField();
netIncomeJTextField.setBounds(200, 140, 100, 20);
netIncomeJTextField.setFont(new Font("Default", Font.PLAIN, 12));
netIncomeJTextField.setHorizontalAlignment(JTextField.CENTER);
netIncomeJTextField.setForeground(black);
netIncomeJTextField.setBackground(white);
netIncomeJTextField.setEditable(false);
contentPane.add(netIncomeJTextField);
// control
enterJButton = new JButton();
enterJButton.setBounds(25, 300, 100, 20);
enterJButton.setFont(new Font("Default", Font.PLAIN, 12));
enterJButton.setText("Enter");
enterJButton.setForeground(black);
enterJButton.setBackground(white);
contentPane.add(enterJButton);
enterJButton.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
enterJButtonActionPerformed(event);
}
}
);
clearJButton = new JButton();
clearJButton.setBounds(150, 300, 100, 20);
clearJButton.setFont(new Font("Default", Font.PLAIN, 12));
clearJButton.setText("Clear");
clearJButton.setForeground(black);
clearJButton.setBackground(white);
contentPane.add(clearJButton);
clearJButton.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
clearJButtonActionPerformed(event);
}
}
);
closeJButton = new JButton();
closeJButton.setBounds(275, 300, 100, 20);
closeJButton.setFont(new Font("Default", Font.PLAIN, 12));
closeJButton.setText("Close");
closeJButton.setForeground(black);
closeJButton.setBackground(white);
contentPane.add(closeJButton);
closeJButton.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
closeJButtonActionPerformed(event);
}
}
);
// set properties of application’s window
setTitle("Income Tax"); // set title bar text
setSize(400, 400); // set window size
setVisible(true); // display window
}
// main method
public static void main(String[] args)
{
IncomeTax application = new IncomeTax();
application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void enterJButtonActionPerformed(ActionEvent event)
{
// get input values
grossIncome = Double.parseDouble(grossIncomeJTextField.getText());
// calculate values
taxRate = .20;
tax = grossIncome * taxRate;
netIncome = grossIncome - tax;
// display results
currency = new DecimalFormat("$0.00");
taxJTextField.setText("" + currency.format(tax));
netIncomeJTextField.setText("" + currency.format(netIncome));
}
public void clearJButtonActionPerformed(ActionEvent event)
{
grossIncomeJTextField.setText("");
grossIncomeJTextField.requestFocusInWindow();
taxJTextField.setText("");
netIncomeJTextField.setText("");
}
public void closeJButtonActionPerformed(ActionEvent event)
{
System.exit(0);
}
}
