gistfile1.java

import javax.swing.*;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class CurrencyExchange { // I'm not an actionListener!
	String[] differentCurrency = {"US Dollars","Japanese YEN","Chinese YUAN", "Korean WON"};
	JFrame frame;
	JPanel contentPane;
	JLabel label, result;
	JButton button;
	// lesson 1. proper naming (start w/ lowercase for typical variable names)
	// sorry, I can't read code easily without such conventions
	JTextField initial, result1;
	
	// moved JComboBox!
	JComboBox list;

	public CurrencyExchange(){
		/* Create and set up the frame */

		frame = new JFrame("Currency Converter");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		/* Create a content pane */
		contentPane = new JPanel();
		/* Create and add label */


		label = new JLabel("Enter Amount in New Taiwan Dollars (NTD):");
		contentPane.add(label);

		initial = new JTextField(6);
		contentPane.add(initial);


		list = new JComboBox(differentCurrency);
		contentPane.add(list);


		JButton run= new JButton("Convert");
		// behold an anonymous ActionListener
		// you don't have to test for the source anymore, only this button can call it
		run.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent event) {
				String firstNumber = initial.getText();
				double finalresult;
				String course = (String) list.getSelectedItem();
				if(course.equalsIgnoreCase("US Dollars")) {
					finalresult = Double.parseDouble(firstNumber) * 0.03;
					result1.setText(finalresult + "");
				}
			}
		});
		contentPane.add(run);

		result = new JLabel("Converted Result");
		contentPane.add(result);

		result1 = new JTextField(6);
		// result1.addActionListener(this);
		contentPane.add(result1);


		contentPane.setLayout(new GridLayout(10, 0, 0, 0));
		/* Add content pane to frame */
		frame.setContentPane(contentPane);
		/* Size and then display the frame. */
		frame.pack();
		frame.setVisible(true);


	}
	private static void runGUI(){
		JFrame.setDefaultLookAndFeelDecorated(false);
		CurrencyExchange greeting = new CurrencyExchange();
	}
	public static void main(String[] args){
		javax.swing.SwingUtilities.invokeLater(new Runnable(){
			public void run (){
				runGUI();
			}
		});}

}