Since my requirement is override the existing textView get from findViewById(getResources().getIdentifier("xxx", "id", "android"));
, so I can't simply try onDraw()
of other answer.
But I just figure out the correct steps to fixed my problem, here is the final result from Layout Inspector:

Since what I wanted is merely remove the top spaces, so I don't have to choose other font to remove bottom spaces.
Here is the critical code to fixed it:
Typeface mfont = Typeface.createFromAsset(getResources().getAssets(), "fonts/myCustomFont.otf");
myTextView.setTypeface(mfont);
myTextView.setPadding(0, 0, 0, 0);
myTextView.setIncludeFontPadding(false);
The first key is set custom font "fonts/myCustomFont.otf" which has the space on bottom but not on the top, you can easily figure out this by open otf file and click any font in android Studio:

As you can see, the cursor on the bottom has extra spacing but not on the top, so it fixed my problem.
The second key is you can't simply skip any of the code, otherwise it might not works. That's the reason you can found some people comment that an answer is working and some other people comment that it's not working.
Let's illustrated what will happen if I remove one of them.
Without setTypeface(mfont);
:

Without setPadding(0, 0, 0, 0);
:

Without setIncludeFontPadding(false);
:

Without 3 of them (i.e. the original):
