How is the presence of a Looper in a thread checked?

Looper myLooper = Looper.myLooper();
if (myLooper != null) {
    // Looper is present in the current thread
} else {
    // Looper is absent in the current thread
}

Looper.myLooper() returns an instance of Looper associated with the current thread. If the Looper is not initialized in this thread, the method will return null. Checking for null allows you to determine the presence of a Looper.