Android 如何判断当前线程是否是主线程

public boolean isMainThread() {
    return Looper.getMainLooper() == Looper.myLooper();
}

public boolean isMainThread() {
    return Looper.getMainLooper().getThread() == Thread.currentThread();
}

public boolean isMainThread() {
    return Looper.getMainLooper().getThread().getId() == Thread.currentThread().getId();
}