ProgressMonitorInputStreamTest.java Source code

Introduction

Here is the source code for ProgressMonitorInputStreamTest.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.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Scanner;

import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.ProgressMonitorInputStream;
import javax.swing.SwingWorker;

/**
 * A program to test a progress monitor input stream.
 * @version 1.04 2007-08-01
 * @author Cay Horstmann
 */
public class ProgressMonitorInputStreamTest {
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                JFrame frame = new TextFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setVisible(true);
            }
        });
    }
}

/**
 * A frame with a menu to load a text file and a text area to display its contents. The text area is
 * constructed when the file is loaded and set as the content pane of the frame when the loading is
 * complete. That avoids flicker during loading.
 */
class TextFrame extends JFrame {
    public TextFrame() {
        setTitle("ProgressMonitorInputStreamTest");
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

        textArea = new JTextArea();
        add(new JScrollPane(textArea));

        chooser = new JFileChooser();
        chooser.setCurrentDirectory(new File("."));

        JMenuBar menuBar = new JMenuBar();
        setJMenuBar(menuBar);
        JMenu fileMenu = new JMenu("File");
        menuBar.add(fileMenu);
        openItem = new JMenuItem("Open");
        openItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                try {
                    openFile();
                } catch (IOException exception) {
                    exception.printStackTrace();
                }
            }
        });

        fileMenu.add(openItem);
        exitItem = new JMenuItem("Exit");
        exitItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                System.exit(0);
            }
        });
        fileMenu.add(exitItem);
    }

    /**
     * Prompts the user to select a file, loads the file into a text area, and sets it as the content
     * pane of the frame.
     */
    public void openFile() throws IOException {
        int r = chooser.showOpenDialog(this);
        if (r != JFileChooser.APPROVE_OPTION)
            return;
        final File f = chooser.getSelectedFile();

        // set up stream and reader filter sequence

        FileInputStream fileIn = new FileInputStream(f);
        ProgressMonitorInputStream progressIn = new ProgressMonitorInputStream(this, "Reading " + f.getName(),
                fileIn);
        final Scanner in = new Scanner(progressIn);

        textArea.setText("");

        SwingWorker<Void, Void> worker = new SwingWorker<Void, Void>() {
            protected Void doInBackground() throws Exception {
                while (in.hasNextLine()) {
                    String line = in.nextLine();
                    textArea.append(line);
                    textArea.append("\n");
                }
                in.close();
                return null;
            }
        };
        worker.execute();
    }

    private JMenuItem openItem;
    private JMenuItem exitItem;
    private JTextArea textArea;
    private JFileChooser chooser;

    public static final int DEFAULT_WIDTH = 300;
    public static final int DEFAULT_HEIGHT = 200;
}