Hello!
I'm currently working on a sort of simple imperial-to-metric converter application for myself, but I seem to have hit a snag. I've got the UI built, and the logic for one of the calculations built, but the button to make it all happen is giving me a problem.
import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
import java.awt.*;
import java.awt.event.*;
public class MetricConverterApp extends JFrame implements ActionListener
{
public MetricConverterApp()
{
double kilogram = 0.45359;
//Title section
setTitle("Metric Converter");
setSize(300,150);
setVisible(true);
setResizable(false);
JTabbedPane jtp = new JTabbedPane();
//Builds template of the window
getContentPane().add(jtp);
//creating an instance of the menu bar for across the program
MenuBar mnuBar = new MenuBar();
setMenuBar(mnuBar);
//building and filling the program's File menu
Menu mnuFile = new Menu("File", true);
mnuBar.add(mnuFile);
MenuItem mnuFileExit = new MenuItem("Exit");
mnuFile.add(mnuFileExit);
//building and filling the program's About menu
Menu mnuAbout = new Menu("About", true);
mnuBar.add(mnuAbout);
MenuItem mnuAboutMetricConverter = new MenuItem("About Metric Converter");
mnuAbout.add(mnuAboutMetricConverter);
//adding ActionListener to each of the menu items
mnuFileExit.addActionListener(this);
mnuAboutMetricConverter.addActionListener(this);
//give each menu item an ActionCommand
mnuFileExit.setActionCommand("Exit");
mnuAboutMetricConverter.setActionCommand("About");
JPanel jp1 = new JPanel();//Builds first tab
jp1.setLayout(new BorderLayout());//Sets up layout of first tab
JPanel jp2 = new JPanel();//Builds second tab
jp2.setLayout(new BorderLayout());//Sets up layout of second tab
JPanel jp3 = new JPanel();//Builds third tab
jp3.setLayout(new BorderLayout());//sets up layout of second tab
//Builds prompt for first tab
JLabel weightPrompt = new JLabel();
weightPrompt.setText("Enter the weight in pounds");
jp1.add(weightPrompt, BorderLayout.NORTH);
//Builds text input for first tab
JTextField weightInput = new JTextField();
jp1.add(weightInput, BorderLayout.CENTER);
//Builds button for first tab
JButton metWeight = new JButton("Convert to kilograms");
jp1.add(metWeight, BorderLayout.EAST);
metWeight.addActionListener(this);
//Builds text output for first tab
JTextField weightOutput = new JTextField();
jp1.add(weightOutput, BorderLayout.SOUTH);
//Builds prompt for second tab
JLabel lengthPrompt = new JLabel();
lengthPrompt.setText("Enter the length in feet");
jp2.add(lengthPrompt, BorderLayout.NORTH);
//Builds text input for first tab
JTextField lengthInput = new JTextField("");
jp2.add(lengthInput, BorderLayout.CENTER);
//Builds button for second tab
JButton metLength = new JButton("Convert to meters");
jp2.add(metLength, BorderLayout.EAST);
//Builds text output for second tab
JTextField lengthOutput = new JTextField();
jp2.add(lengthOutput, BorderLayout.SOUTH);
//Build prompt for third tab
JLabel tempPrompt = new JLabel();
tempPrompt.setText("Enter the temperature in farenheit");
jp3.add(tempPrompt, BorderLayout.NORTH);
//Builds text input for third tab
JTextField tempInput = new JTextField("");
jp3.add(tempInput, BorderLayout.CENTER);
//Builds button for third tab
JButton metTemp = new JButton("Convert to celcius");
jp3.add(metTemp, BorderLayout.EAST);
//Builds text output for third tab
JTextField tempOutput = new JTextField();
jp3.add(tempOutput, BorderLayout.SOUTH);
//Adds tabs to pane
jtp.addTab("Weight", jp1);
jtp.addTab("Length", jp2);
jtp.addTab("Temperature", jp3);
}
@Override
public void actionPerformed(ActionEvent e)
{
//ActionListener for menu item clicks
String arg = e.getActionCommand();
if (arg == "Exit")
System.exit(0);
if (arg == "About")
{
String message = "Metric Converter v1.0\nDesigned by:\nMe\nFebruary 19, 2011";
JOptionPane.showMessageDialog(null,message,"About Metric Converter", JOptionPane.INFORMATION_MESSAGE);
}
if(e.getSource() == metWeight)
{
double value = Double.parseDouble(weightInput.getText());
weightOutput.setText((value * kilogram) + "");
}
}
//main method
public static void main (String []args)
{
MetricConverterApp tab = new MetricConverterApp();
}
}The problem lies in lines 137 - 141. the metWeight and the kilogram variables are kicking back the error of "Cannot be resolved to a variable", and then the weightInput and weightOutput are showing an error of just "Cannot be resolved". When I run the program, I enter in the weight in pounds, then click the button to calculate it to kilograms, but nothing happens, and I think it's somewhere in that bit of code. I was wondering if anyone had any idea what could be causing this? I'd really appreciate any help.