BirdListGUI

import javax.swing.*;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class BirdListGUI extends JFrame{

    private JPanel listPanel;
    private JPanel buttonPanel;
    private JList birdList;
    private JLabel label;
    private JButton revButton;

    public BirdListGUI() {
        super("Bird List");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        //build panels
        buildListPanel();
        buildButtonPanel();

        //add panels
        add(listPanel, BorderLayout.WEST);
        add(buttonPanel, BorderLayout.SOUTH);
        pack();
        setVisible(true);
    }

    public void buildListPanel() {
        listPanel = new JPanel();
        label = new JLabel("Birds");

        BirdList list = new BirdList();
        try {
            Scanner input1 = new Scanner(new File("birds1.txt"));
            Scanner input2 = new Scanner(new File("birds2.txt"));
            while (input1.hasNext()) //Populate list
                list.insert(input1.nextLine());
            while (input2.hasNext()) //Remove non-indigenous birds
                list.remove(input2.nextLine());
        }
        catch(FileNotFoundException e) {
            System.out.println(e.getMessage());
        }
        list.sort();
        String stringList[] = new String[list.getSize()];
        for (int i = 0; i < stringList.length; i++)
            stringList[i] = list.printSingle(i);

        birdList = new JList(stringList);
        birdList.setVisibleRowCount(6);
        JScrollPane birdListScrollPane = new JScrollPane(birdList);
        listPanel.add(label);
        listPanel.add(birdListScrollPane);
    }

    public void buildButtonPanel() {
        buttonPanel = new JPanel();
        revButton = new JButton("Reverse Order");
        revButton.addActionListener(new ButtonListener());
        buttonPanel.add(revButton);
    }

    class ButtonListener implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            BirdList list = new BirdList();
            try {
                Scanner input1 = new Scanner(new File("birds1.txt"));
                Scanner input2 = new Scanner(new File("birds2.txt"));
                while (input1.hasNext()) //Populate list
                    list.insert(input1.nextLine());
                while (input2.hasNext()) //Remove non-indigenous birds
                    list.remove(input2.nextLine());
            }
            catch(FileNotFoundException ex) {
                System.out.println(ex.getMessage());
            }
            list.sortRev();
            String stringList[] = new String[list.getSize()];
            for (int i = 0; i < stringList.length; i++)
                stringList[i] = list.printSingle(i);
            birdList.setListData(stringList);
        }

    }

    public static void main(String[] args) {
        new BirdListGUI();
    }
}