Run the supplied Runnable on the main thread.

Description

Demo Code

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
//package com.java2s;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;
import android.os.Handler;
import android.os.Looper;

public class Main {
    private static final Object sLock = new Object();
    private static boolean sWillOverride = false;
    private static Handler sUiThreadHandler = null;

    /**/*from w w  w.ja v a  2s .  co  m*/
     * Run the supplied Runnable on the main thread. The method will block until the Runnable
     * completes.
     *
     * @param r The Runnable to run.
     */
    public static void runOnUiThreadBlocking(final Runnable r) {
        if (runningOnUiThread()) {
            r.run();
        } else {
            FutureTask<Void> task = new FutureTask<Void>(r, null);
            postOnUiThread(task);
            try {
                task.get();
            } catch (Exception e) {
                throw new RuntimeException(
                        "Exception occured while waiting for runnable", e);
            }
        }
    }

    /**
     * Run the supplied Callable on the main thread, The method will block until the Callable
     * completes.
     *
     * @param c The Callable to run
     * @return The result of the callable
     * @throws ExecutionException c's exception
     */
    public static <T> T runOnUiThreadBlocking(Callable<T> c)
            throws ExecutionException {
        FutureTask<T> task = new FutureTask<T>(c);
        runOnUiThread(task);
        try {
            return task.get();
        } catch (InterruptedException e) {
            throw new RuntimeException("Interrupted waiting for callable",
                    e);
        }
    }

    /**
     * @return true iff the current thread is the main (UI) thread.
     */
    public static boolean runningOnUiThread() {
        return getUiThreadHandler().getLooper() == Looper.myLooper();
    }

    /**
     * Post the supplied FutureTask to run on the main thread. The method will not block, even if
     * called on the UI thread.
     *
     * @param task The FutureTask to run
     * @return The queried task (to aid inline construction)
     */
    public static <T> FutureTask<T> postOnUiThread(FutureTask<T> task) {
        getUiThreadHandler().post(task);
        return task;
    }

    /**
     * Post the supplied Runnable to run on the main thread. The method will not block, even if
     * called on the UI thread.
     *
     * @param task The Runnable to run
     */
    public static void postOnUiThread(Runnable r) {
        getUiThreadHandler().post(r);
    }

    /**
     * Run the supplied FutureTask on the main thread. The method will block only if the current
     * thread is the main thread.
     *
     * @param task The FutureTask to run
     * @return The queried task (to aid inline construction)
     */
    public static <T> FutureTask<T> runOnUiThread(FutureTask<T> task) {
        if (runningOnUiThread()) {
            task.run();
        } else {
            postOnUiThread(task);
        }
        return task;
    }

    /**
     * Run the supplied Callable on the main thread. The method will block only if the current
     * thread is the main thread.
     *
     * @param c The Callable to run
     * @return A FutureTask wrapping the callable to retrieve results
     */
    public static <T> FutureTask<T> runOnUiThread(Callable<T> c) {
        return runOnUiThread(new FutureTask<T>(c));
    }

    /**
     * Run the supplied Runnable on the main thread. The method will block only if the current
     * thread is the main thread.
     *
     * @param r The Runnable to run
     */
    public static void runOnUiThread(Runnable r) {
        if (runningOnUiThread()) {
            r.run();
        } else {
            getUiThreadHandler().post(r);
        }
    }

    private static Handler getUiThreadHandler() {
        synchronized (sLock) {
            if (sUiThreadHandler == null) {
                if (sWillOverride) {
                    throw new RuntimeException(
                            "Did not yet override the UI thread");
                }
                sUiThreadHandler = new Handler(Looper.getMainLooper());
            }
            return sUiThreadHandler;
        }
    }
}
Run the supplied Runnable on the main thread. - Android java.lang

Description

Demo Code

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