I'm trying to change the font of my textView text but I'm having a fatal error, can you help me? (I added the halohandletter.otf file in the assets folder)

********** the code ***********

// in the onCreate method ..

Typeface myTypeFace = Typeface.createFromAsset(getAs
sets(),"halohandletter.otf"); TextView mainActivity_textView (TextView)findViewById(R.id.mainActivity_textView); mainActivity_textView.setTypeface(myTypeFace);

***********the error************

java.lang.RuntimeException: Unable to start activity ComponentInfo{aou.texit/aou.texit.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setTypeface(android.graphics.Typeface)' on a null object reference