package pl.droidsonroids.gif;import java.util.concurrent.ScheduledThreadPoolExecutor;/** * Default executor for rendering tasks - {
    @link java.util.concurrent.ScheduledThreadPoolExecutor} * with 1 worker thread and {
    @link java.util.concurrent.ThreadPoolExecutor.DiscardPolicy}. */final class GifRenderingExecutor extends ScheduledThreadPoolExecutor {    private GifRenderingExecutor() {        super(1, new DiscardPolicy());    }    @SuppressWarnings("StaticNonFinalField") //double-checked singleton initialization    private static volatile GifRenderingExecutor instance = null;    public static GifRenderingExecutor getInstance() {        if (instance == null) {            synchronized (GifRenderingExecutor.class) {                if (instance == null) {                    instance = new GifRenderingExecutor();                }            }        }        return instance;    }}