Java Tutorial/SWT/ProgressBar

Introducing ProgressBar

Progress bars display incremental progress. ProgressBar Styles:

StyleDescriptionSWT.SMOOTHCreates a progress bar that displays a continuous bar as its indicator. The default is to display a distinctly divided bar.SWT.HORIZONTALCreates a horizontal progress bar.SWT.VERTICALCreates a vertical progress bar.SWT.INDETERMINATECreates a progress bar that constantly cycles, indicating continuous work.

Update a progress bar from another thread

/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
 
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.ProgressBar;
import org.eclipse.swt.widgets.Shell;
public class ProgressBarUpdateAnotherThread {
  public static void main(String[] args) {
    final Display display = new Display();
    Shell shell = new Shell(display);
    final ProgressBar bar = new ProgressBar(shell, SWT.SMOOTH);
    bar.setBounds(10, 10, 200, 32);
    shell.open();
    final int maximum = bar.getMaximum();
    new Thread() {
      public void run() {
        for (final int[] i = new int[1]; i[0] <= maximum; i[0]++) {
          try {
            Thread.sleep(100);
          } catch (Throwable th) {
          }
          if (display.isDisposed())
            return;
          display.asyncExec(new Runnable() {
            public void run() {
              if (bar.isDisposed())
                return;
              bar.setSelection(i[0]);
            }
          });
        }
      }
    }.start();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
}

Update a progress bar from the UI thread

import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.ProgressBar;
import org.eclipse.swt.widgets.Shell;
public class ProgressBarUpdateUIThread {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    ProgressBar bar = new ProgressBar(shell, SWT.SMOOTH);
    bar.setBounds(10, 10, 200, 32);
    shell.open();
    for (int i = 0; i <= bar.getMaximum(); i++) {
      try {
        Thread.sleep(100);
      } catch (Throwable th) {
      }
      bar.setSelection(i);
    }
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
}

Using the SWT.INDETERMINATE style: the operation is happening but doesn"t know when it"ll finish.

import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.ProgressBar;
import org.eclipse.swt.widgets.Shell;
public class ProgressBarExample {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new GridLayout());
    // Create an indeterminate ProgressBar
    ProgressBar pb2 = new ProgressBar(shell, SWT.HORIZONTAL | SWT.INDETERMINATE);
    pb2.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));

    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
  }
}

Using Thread to update ProgressBar value

import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.ProgressBar;
import org.eclipse.swt.widgets.Shell;
public class ProgressBarExample {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new GridLayout());
    // Create a smooth ProgressBar
    ProgressBar pb1 = new ProgressBar(shell, SWT.HORIZONTAL | SWT.SMOOTH);
    pb1.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
    pb1.setMinimum(0);
    pb1.setMaximum(30);
    // Start the first ProgressBar
    new LongRunningOperation(display, pb1).start();
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
  }
}
class LongRunningOperation extends Thread {
  private Display display;
  private ProgressBar progressBar;
  public LongRunningOperation(Display display, ProgressBar progressBar) {
    this.display = display;
    this.progressBar = progressBar;
  }
  public void run() {
    for (int i = 0; i < 30; i++) {
      try {
        Thread.sleep(1000);
      } catch (InterruptedException e) {
      }
      display.asyncExec(new Runnable() {
        public void run() {
          if (progressBar.isDisposed())
            return;
          progressBar.setSelection(progressBar.getSelection() + 1);
        }
      });
    }
  }
}