examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet130.java

/*******************************************************************************
 * Copyright (c) 2000, 2016 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Lars Vogel <Lars.Vogel@vogella.com> - Bug 502845
 *******************************************************************************/
package org.eclipse.swt.snippets;

/*
 * BusyIndicator example snippet: display busy cursor during long running task
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */

import static org.eclipse.swt.events.SelectionListener.*;

import org.eclipse.swt.*;
import org.eclipse.swt.custom.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

public class Snippet130 {

	public static void main(String[] args) {
		final Display display = new Display();
		final Shell shell = new Shell(display);
		shell.setText("Snippet 130");
		shell.setLayout(new GridLayout());
		final Text text = new Text(shell, SWT.MULTI | SWT.BORDER | SWT.V_SCROLL);
		text.setLayoutData(new GridData(GridData.FILL_BOTH));
		final int[] nextId = new int[1];
		Button b = new Button(shell, SWT.PUSH);
		b.setText("invoke long running job");
		b.addSelectionListener(widgetSelectedAdapter(e-> {
				Runnable longJob = new Runnable() {
					boolean done = false;
					int id;
					@Override
					public void run() {
						Thread thread = new Thread(() -> {
							id = nextId[0]++;
							display.syncExec(() -> {
								if (text.isDisposed()) return;
								text.append("\nStart long running task "+id);
							});
							for (int i = 0; i < 100000; i++) {
								if (display.isDisposed()) return;
								System.out.println("do task that takes a long time in a separate thread "+id);
							}
							if (display.isDisposed()) return;
							display.syncExec(() -> {
								if (text.isDisposed()) return;
								text.append("\nCompleted long running task "+id);
							});
							done = true;
							display.wake();
						});
						thread.start();
						while (!done && !shell.isDisposed()) {
							if (!display.readAndDispatch())
								display.sleep();
						}
					}
				};
				BusyIndicator.showWhile(display, longJob);
			}));
		shell.setSize(250, 150);
		shell.open();
		while (!shell.isDisposed()) {
			if (!display.readAndDispatch())
				display.sleep();
		}
		display.dispose();
	}
}