Set custom font to TextView.
You have two ways, first see first way:
1. Add your font files to assets folder, if not exist assets folder create its.
2. Create CustomTypeface class, for examples:
import android.content.Context;
import android.content.res.AssetManager;
import android.graphics.Typeface;
public class CustomTypeface {
    private static Typeface typefaseArialCondIt;
    private static Typeface typefaseArialBold;
    private static Typeface typefaseArialRegular;
    public CustomTypeface() {
    }
    public CustomTypeface(Context context) {
        AssetManager assets = context.getAssets();
        CustomTypeface.typefaseArialCondIt = Typeface.createFromAsset(assets, "fonts/ArialCondIt.otf");
        CustomTypeface.typefaseArialBold = Typeface.createFromAsset(assets, "fonts/ArialBold.otf");
        CustomTypeface.typefaseArialRegular = Typeface.createFromAsset(assets, "fonts/ArialRegular.otf");
    }
    public static Typeface gettypefaseArialCondIt() {
        return typefaseArialCondIt;
    }
    public static Typeface settypefaseArialCondIt(Typeface typefaseArialCondIt) {
        return CustomTypeface.typefaseArialCondIt = typefaseArialCondIt;;
    }
    public static Typeface gettypefaseArialBold() {
        return typefaseArialBold;
    }
    public static Typeface settypefaseArialBold(Typeface typefaseArialBold) {
        return CustomTypeface.typefaseArialBold = typefaseArialBold;;
    }
    public static Typeface gettypefaseArialRegular() {
        return typefaseArialRegular;
    }
    public static void settypefaseArialRegular(Typeface typefaseArialRegular) {
        CustomTypeface.typefaseArialRegular = typefaseArialRegular;
    }
}
3. And set custom font to TextView:
TextView yourTextView = (TextView) findViewById(R.id.textView1);
yourTextView.setTypeface(CustomTypeface.gettypefaseArialRegular);
Or second way, create custom TextView with your fonts:
import android.content.Context;
import android.graphics.Typeface;
import android.util.AttributeSet;
import android.widget.TextView;
public class ArialTextView extends TextView {
    public ArialTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }
    public ArialTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    public ArialTextView(Context context) {
        super(context);
    }
    @Override
    public void setTypeface(Typeface tf, int style) {
        if (style == Typeface.BOLD) {
            setTypeface(Typeface.createFromAsset(getContext().getAssets(), "fonts/ArialBold.otf"));
        } else if (style == Typeface.NORMAL) {
            setTypeface(Typeface.createFromAsset(getContext().getAssets(), "fonts/ArialRegular.otf"));
        } else if (style == Typeface.ITALIC) {
            setTypeface(Typeface.createFromAsset(getContext().getAssets(), "fonts/ArialCondIt.otf"));
        }
    }
}
And in the layout xml you can create custom TextView, for example:
<com.your.package.ArialTextView
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:textAppearance="?android:attr/textAppearanceMedium"
     android:text="TextView with your custom font"/>