判断是否在主线程

public static boolean isOnMainThread() {
  return Looper.myLooper() == Looper.getMainLooper();
  return Thread.currentThread() == Looper.getMainLooper().getThread();
}

public static void assertMainThread() {
  if (!isOnMainThread()) {
    throw new IllegalArgumentException("You must call this method on the main thread");
  }
}