How to check if current thread is not main thread

I need to check if the thread running a certain piece of code is the main (UI) thread or not. How can I achieve this?

Looper.myLooper() == Looper.getMainLooper()

if this returns true, then you're on the UI thread!

you can use below code to know if current thread is UI/Main thread or not

if(Looper.myLooper() == Looper.getMainLooper()) {
   // Current Thread is Main Thread.
}

or you can also use this

if(Looper.getMainLooper().getThread() == Thread.currentThread()) {
   // Current Thread is Main Thread.
}

Here is similar question

The best way is the clearest, most robust way: *

Thread.currentThread().equals( Looper.getMainLooper().getThread() )

Or, if the runtime platform is API level 23 (Marshmallow 6.0) or higher:

Looper.getMainLooper().isCurrentThread()

See the Looper API. Note that calling Looper.getMainLooper() involves synchronization (see the source). You might want to avoid the overhead by storing the return value and reusing it.

   * credit greg7gkb and 2cupsOfTech

Summarizing the solutions, I think that's the best one:

boolean isUiThread = VERSION.SDK_INT >= VERSION_CODES.M 
    ? Looper.getMainLooper().isCurrentThread()
    : Thread.currentThread() == Looper.getMainLooper().getThread();

And, if you wish to run something on the UI thread, you can use this:

new Handler(Looper.getMainLooper()).post(new Runnable() {
    @Override
    public void run() {
       //this runs on the UI thread
    }
});