Scala example source code file (ThreadHelpers.java)

This example Scala source code file (ThreadHelpers.java) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

actor, nullpointerexception, runnable, thread, threadhelpers, threadpool, throwable, uncaughtexceptionhandler

The ThreadHelpers.java Scala example source code

/*
 * Written by Dawid Kurzyniec and released to the public domain, as explained
 * at http://creativecommons.org/licenses/publicdomain
 */
package scala.actors.threadpool.helpers;

/**
 * Emulation of some new functionality present in java.lang.Thread in J2SE 5.0.
 *
 * @author Dawid Kurzyniec
 * @version 1.0
 */
public class ThreadHelpers {

    private ThreadHelpers() {}

    /**
     * Returns wrapped runnable that ensures that if an exception occurs
     * during the execution, the specified exception handler is invoked.
     * @param runnable runnable for which exceptions are to be intercepted
     * @param handler the exception handler to call when exception occurs
     *        during execution of the given runnable
     * @return wrapped runnable
     */
    public static Runnable assignExceptionHandler(final Runnable runnable,
                                                  final UncaughtExceptionHandler handler)
    {
        if (runnable == null || handler == null) {
            throw new NullPointerException();
        }
        return new Runnable() {
            public void run() {
                try {
                    runnable.run();
                }
                catch (Throwable error) {
                    try {
                        handler.uncaughtException(Thread.currentThread(), error);
                    }
                    catch (Throwable ignore) {}
                }
            }
        };
    }

    /**
     * Abstraction of the exception handler which receives notifications of
     * exceptions occurred possibly in various parts of the system. Exception
     * handlers present attractive approach to exception handling in multi-threaded
     * systems, as they can handle exceptions that occurred in different threads.
     * <p>
     * This class is analogous to Thread.UncaughtExceptionHandler in J2SE 5.0.
     * Obviously you cannot use it the same way, e.g. you cannot assign the
     * handler to the thread so that it is invoked when thread terminates.
     * However, it can be {@link ThreadHelpers#assignExceptionHandler emulated}.
     */
    public static interface UncaughtExceptionHandler {
        /**
         * Notification of the uncaught exception that occurred within specified
         * thread.
         * @param thread the thread where the exception occurred
         * @param error the exception
         */
        void uncaughtException(Thread thread, Throwable error);
    }
}