There is another solution if you want to support multiple fonts within a TextView but they are not supported within a single ttf:
Use the following code:(I'm using Bangla and Tamil font)
  TextView txt = (TextView) findViewById(R.id.custom_fonts);  
        txt.setTextSize(30);
        Typeface font = Typeface.createFromAsset(getAssets(), "Akshar.ttf");
        Typeface font2 = Typeface.createFromAsset(getAssets(), "bangla.ttf");   
        SpannableStringBuilder SS = new SpannableStringBuilder("আমারநல்வரவு");
        SS.setSpan (new CustomTypefaceSpan("", font2), 0, 4,Spanned.SPAN_EXCLUSIVE_INCLUSIVE);
        SS.setSpan (new CustomTypefaceSpan("", font), 4, 11,Spanned.SPAN_EXCLUSIVE_INCLUSIVE);
        txt.setText(SS);
The outcome is:

CustomTypefaceSpan Class:
package my.app;
import android.graphics.Paint;
import android.graphics.Typeface;
import android.text.TextPaint;
import android.text.style.TypefaceSpan;
public class CustomTypefaceSpan extends TypefaceSpan {
private final Typeface newType;
public CustomTypefaceSpan(String family, Typeface type) {
    super(family);
    newType = type;
}
@Override
public void updateDrawState(TextPaint ds) {
    applyCustomTypeFace(ds, newType);
}
@Override
public void updateMeasureState(TextPaint paint) {
    applyCustomTypeFace(paint, newType);
}
private static void applyCustomTypeFace(Paint paint, Typeface tf) {
    int oldStyle;
    Typeface old = paint.getTypeface();
    if (old == null) {
        oldStyle = 0;
    } else {
        oldStyle = old.getStyle();
    }
    int fake = oldStyle & ~tf.getStyle();
    if ((fake & Typeface.BOLD) != 0) {
        paint.setFakeBoldText(true);
    }
    if ((fake & Typeface.ITALIC) != 0) {
        paint.setTextSkewX(-0.25f);
    }
    paint.setTypeface(tf);
}
}
Reference