Main.java Source code

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Here is the source code for Main.java

Source

/*
   This program is a part of the companion code for Core Java 8th ed.
   (http://horstmann.com/corejava)
    
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
    
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
    
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.List;

import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingWorker;

/**
 * This program demonstrates the use of a progress bar to monitor the progress
 * of a thread.
 * 
 * @version 1.04 2007-08-01
 * @author Cay Horstmann
 */
public class Main {
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                JFrame frame = new ProgressBarFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setVisible(true);
            }
        });
    }
}

/**
 * A frame that contains a button to launch a simulated activity, a progress
 * bar, and a text area for the activity output.
 */
class ProgressBarFrame extends JFrame {
    public ProgressBarFrame() {
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

        // this text area holds the activity output
        textArea = new JTextArea();

        // set up panel with button and progress bar

        final int MAX = 1000;
        JPanel panel = new JPanel();
        startButton = new JButton("Start");
        progressBar = new JProgressBar(0, MAX);
        progressBar.setStringPainted(true);
        panel.add(startButton);
        panel.add(progressBar);

        checkBox = new JCheckBox("indeterminate");
        checkBox.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                progressBar.setIndeterminate(checkBox.isSelected());
                progressBar.setStringPainted(!progressBar.isIndeterminate());
            }
        });
        panel.add(checkBox);
        add(new JScrollPane(textArea), BorderLayout.CENTER);
        add(panel, BorderLayout.SOUTH);

        // set up the button action

        startButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                startButton.setEnabled(false);
                activity = new SimulatedActivity(MAX);
                activity.execute();
            }
        });
    }

    private JButton startButton;
    private JProgressBar progressBar;
    private JCheckBox checkBox;
    private JTextArea textArea;
    private SimulatedActivity activity;

    public static final int DEFAULT_WIDTH = 400;
    public static final int DEFAULT_HEIGHT = 200;

    class SimulatedActivity extends SwingWorker<Void, Integer> {
        /**
         * Constructs the simulated activity that increments a counter from 0 to a
         * given target.
         * 
         * @param t
         *          the target value of the counter.
         */
        public SimulatedActivity(int t) {
            current = 0;
            target = t;
        }

        protected Void doInBackground() throws Exception {
            try {
                while (current < target) {
                    Thread.sleep(100);
                    current++;
                    publish(current);
                }
            } catch (InterruptedException e) {
            }
            return null;
        }

        protected void process(List<Integer> chunks) {
            for (Integer chunk : chunks) {
                textArea.append(chunk + "\n");
                progressBar.setValue(chunk);
            }
        }

        protected void done() {
            startButton.setEnabled(true);
        }

        private int current;
        private int target;
    }
}