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// This program displays the number of miles that the car may be driven per gallon of gas.
import java.util.*;
import javax.swing.*; // Needed for JOptionPane.
import java.text.DecimalFormat; // Keeping proper decimal format.
import java.awt.*; // Needed for BorderLayout class.
import java.awt.event.*;
// MPG.java Simple program to compute gas mileage
class MPG {
/**
* Ask user for input, and compute result
*/
public static void main(String[] args) {
if (args.length!=3) {
System.out.println("Usage: java MPG start end gallons");
System.exit(0);
}
int start = Integer.parseInt(args[0]);
int end = Integer.parseInt(args[1]);
double gallons = Double.parseDouble(args[2]);
int distance = end - start;
double mpg = distance/gallons;
System.out.println("MPG is " + mpg);
}
}
public class MPGCalculatorWindow extends JFrame
{
private JPanel panel; // A holding panel
private JLabel messageLabel; // A message to the user
private JLabel messageLabel1; // A message to the user
private JTextField TextField; // To hold user input for gallons of gas
private JTextField TextField1;
private JPanel ButtonPanel; // To hold the buttons
private JButton calcButton; // To calculate miles per gallon (MPG)
private JButton exitButton; // To exit the application
private final int WINDOW_WIDTH = 500; // Window width
private final int WINDOW_HEIGHT = 200; // Window height
/**
Constructor
*/
public MPGCalculatorWindow()
{
// Set the title bar text.
setTitle("MPG Calculator");
// Set the size of the window.
setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
// Create a BorderLayout manager to content pane.
setLayout(new BorderLayout(13,15));
// Specify an action for the close button.
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Build the panel and add it to the frame.
buildPanel();
//Add the panel and add it to the frame.
add(panel);
// Display the window.
setVisible(true);
}
/**
The buildButtonPanel method adds a label, textfield, and buttons to a pane
*/
private void buildPanel()
{
// Create a panel for the buttons.
ButtonPanel = new JPanel();
// Create the label.
messageLabel = new JLabel("Enter number of miles " +
"driven on a full tank:");
// Create a text field.
TextField = new JTextField(20);
// Create the label.
messageLabel1 = new JLabel("Enter number of gallons of gas " +
"your car holds:");
//Create the text field.
TextField1 = new JTextField(20);
// Create the buttons with captions
calcButton = new JButton("Calculate");
exitButton = new JButton("Exit");
//Register the action listeners to the buttons.
calcButton.addActionListener(new CalcButtonListener());
exitButton.addActionListener(new ExitButtonListener());
// Add buttons to the button panel
ButtonPanel.add(calcButton);
ButtonPanel.add(exitButton);
// Create a panel object and add let the panel reference to it.
panel = new JPanel();
// Add the label, textfield, and button components to the panel.
panel.add(messageLabel);
panel.add(messageLabel1);
panel.add(TextField);
panel.add(TextField1);
panel.add(calcButton);
panel.add(exitButton);
}
/** Private inner class that handles the event when the user clicks any of the two buttons.
*/
private class CalcButtonListener implements ActionListener
{
/**
The actionPerformed method executes when the user clicks on the Calculate button.
@param e the event object.
*/
public void actionPerformed(ActionEvent e)
{
String input1;
String input2;
double total_miles;
double gallons;
double MPG;
input1 = TextField.getText();
input2 = TextField1.getText();
total_miles = Double.parseDouble(input1);
gallons = Double.parseDouble(input2);
// Formula for finding the miles-per-gallon.
MPG = total_miles/gallons;
// Create a DecimalFormat object.
DecimalFormat formatter = new DecimalFormat("#00.00");
// Display the calculation
JOptionPane.showMessageDialog(null,"The total miles that your car may be driven per gallon of gas: " +
formatter.format(MPG));
}
}
/** Private inner class that handles the event when the user clicks the Exit button.
*/
private class ExitButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
System.exit(0);
}
}
}
What I am saying is if it compiles correctly, whyam I getting this error when trying to run it in TextPad 6.0
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