java捕获进程时间实时进度条

Question

new Scanner(new URL("SOME_URL.txt").openStream(), "UTF-8").useDelimiter("\\A").next();

Using this ^ I get the data from a .txt-File which I save in a String.

For my progress bar , I wondered if it would be possible for jobs like that (or in general for methods etc.) to count (or sth. like that) the time it needed to be finished. So that I can show in real time process time in my bar .

Is this somehow possible?

EDIT:

package app.gui;

    import java.awt.BorderLayout;
    import java.awt.EventQueue;
    import java.net.URL;
    import java.util.Scanner;

    import javax.swing.JFrame;
    import javax.swing.JPanel;
    import javax.swing.JProgressBar;
    import javax.swing.UIManager;
    import javax.swing.UnsupportedLookAndFeelException;

    import org.apache.commons.io.IOUtils;

    public class Updater {

        private JFrame frame;
        private static String rawG;
        private static String versI;

        public static void main(String[] args) {
            EventQueue.invokeLater(new Runnable() {
                public void run() {
                    try {
                        rawG = new Scanner(new URL("SOME_URL.txt").openStream(), "UTF-8").useDelimiter("\\A").next();
                        versI = IOUtils.toString(getClass().getClassLoader().getResourceAsStream("version.txt"));
                    } catch (Exception e) {
                        System.out.println("error class Updater try/catch raw github");
                    }
                    if (Integer.parseInt(rawG.split("\\.")[0]) < Integer.parseInt(versI.split("\\.")[0])) {
                        System.out.println("Version check failure, update needed");
                        try {
                            Updater window = new Updater();
                            window.frame.setVisible(true);
                        } catch (Exception e) {
                            System.out.println("error class Updater try/catch initialize frame");
                        }                   
                    } else {
                        System.out.println("Version check correct, no update needed");
                    }
                }
            });
        }

        public Updater() {
            initialize();
        }

        private void initialize() {
            try {
                UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
            } catch (ClassNotFoundException | InstantiationException | IllegalAccessException
                    | UnsupportedLookAndFeelException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            frame = new JFrame();
            frame.setBounds(100, 100, 450, 300);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

            JPanel panel = new JPanel();
            frame.getContentPane().add(panel, BorderLayout.SOUTH);
            panel.setLayout(new BorderLayout(0, 0));

            JProgressBar progressBar = new JProgressBar();
            progressBar.setStringPainted(true);
            panel.add(progressBar, BorderLayout.NORTH);
        }

    }

Answer 1

Is it possible? Yes. Is it possible when using Scanner.next() to read the contents of the URL? No.

You will need to read the bytes yourself, and count them:

URL url = new URL("SOME_URL.txt");
URLConnection conn = url.openConnection();

ByteBuffer buffer = ByteBuffer.allocate(conn.getContentLength());
EventQueue.invokeLater(() -> progressBar.setMaximum(buffer.limit()));
EventQueue.invokeLater(() -> progressBar.setValue(0));
try (ReadableByteChannel channel = Channels.newChannel(conn.getInputStream())) {
    while (channel.read(buffer) >= 0) {
        EventQueue.invokeLater(() -> progressBar.setValue(buffer.position()));
    }
}

buffer.flip();
String rawG = StandardCharsets.UTF_8.decode(buffer).toString();