As of Android version 23, You can test it like this:
Typeface typeface;
//initialize the custom font here
//enter the character to test
String charToTest="u0978";
Paint paint=new Paint();
paint.setTypeface(typeface);
boolean hasGlyph=paint.hasGlyph(charToTest);
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…