UnderlineTextView (Java & Kotlin)

UnderlineTextView.java

public class UnderlineTextView extends TextView {
  private Context context;
  private int textColor;

  public UnderlineTextView(Context context) {
    this(context, null);
  }

  public UnderlineTextView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public UnderlineTextView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init(context);
  }

  @TargetApi(Build.VERSION_CODES.LOLLIPOP)
  public UnderlineTextView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
    super(context, attrs, defStyleAttr, defStyleRes);
    init(context);
  }

  private void init(Context context) {
    this.context = context;
  }

  @Override public void setText(CharSequence text, BufferType type) {
    SpannableString spannableString = new SpannableString(text);
    spannableString.setSpan(new UnderlineSpan(), 0, spannableString.length(), 0);
    super.setText(spannableString, type);
  }

  @SuppressLint("InlinedApi") @Override public boolean onTouchEvent(MotionEvent event) {
    if (isClickable()) {
      if (event.getAction() == MotionEvent.ACTION_DOWN) {
        textColor = getCurrentTextColor();
        setTextColor(
            getColorFromTheme(context, android.R.attr.colorAccent, lightenColor(textColor, 0.5f)));
      } else if (event.getAction() == MotionEvent.ACTION_UP) {
        setTextColor(textColor);
      }
    }
    return super.onTouchEvent(event);
  }

  private int getColorFromTheme(Context context, int id, int defaultValue) {
    TypedValue value = new TypedValue();
    try {
      Resources.Theme theme = context.getTheme();
      if (theme != null && theme.resolveAttribute(id, value, true)) {
        if (value.type >= TypedValue.TYPE_FIRST_INT && value.type <= TypedValue.TYPE_LAST_INT) {
          return value.data;
        } else if (value.type == TypedValue.TYPE_STRING) {
          return ContextCompat.getColor(context, value.resourceId);
        }
      }
    } catch (Exception ignored) {
    }
    return defaultValue;
  }

  private int lightenColor(int color, float factor) {
    int red = (int) ((Color.red(color) * (1 - factor) / 255 + factor) * 255);
    int green = (int) ((Color.green(color) * (1 - factor) / 255 + factor) * 255);
    int blue = (int) ((Color.blue(color) * (1 - factor) / 255 + factor) * 255);
    return Color.argb(Color.alpha(color), red, green, blue);
  }
}

UnderlineTextView.kt

class UnderlineTextView @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0) : AppCompatTextView(
    context, attrs, defStyleAttr) {
  private val originalTextColor = textColors.defaultColor

  override fun setText(text: CharSequence, type: TextView.BufferType) {
    val spannableString = SpannableString(text)
    spannableString.setSpan(UnderlineSpan(), 0, spannableString.length, 0)
    super.setText(spannableString, type)
  }

  override fun onTouchEvent(event: MotionEvent): Boolean {
    if (hasOnClickListeners()) when (event.action) {
      MotionEvent.ACTION_DOWN -> setTextColor(highlightColor)
      MotionEvent.ACTION_UP -> {
        setTextColor(originalTextColor)
        return performClick()
      }
    }
    return super.onTouchEvent(event)
  }

  override fun performClick(): Boolean {
    super.performClick()
    return true
  }
}