CustomToolbar with custom Title/Subtitle and NavIcon views

attrs_CustomToolbar.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="CustomToolbar">
        <attr name="titleView" format="reference"/>
        <attr name="subtitleView" format="reference"/>
        <attr name="navigationView" format="reference"/>
    </declare-styleable>
</resources>

CustomToolbar.java

public class CustomToolbar extends android.support.v7.widget.Toolbar {
    private static final String TAG = "CustomToolbar";

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

    public CustomToolbar(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CustomToolbar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        final TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomToolbar, defStyleAttr, 0);
        try {
            mTitleViewId = a.getResourceId(R.styleable.CustomToolbar_titleView, 0);
            mSubtitleViewId = a.getResourceId(R.styleable.CustomToolbar_subtitleView, 0);
            mNavigationViewId = a.getResourceId(R.styleable.CustomToolbar_navigationView, 0);
        } finally {
            a.recycle();
        }
    }

    @IdRes
    private int mTitleViewId;
    @IdRes
    private int mSubtitleViewId;
    @IdRes
    private int mNavigationViewId;
    private Drawable mNavigationIcon;

    @Override
    public void setTitle(CharSequence title) {
        final TextView titleView = (TextView) findViewById(mTitleViewId);
        if (titleView != null) {
            titleView.setText(title);
            titleView.setVisibility(TextUtils.isEmpty(title) ? View.GONE : View.VISIBLE);
        } else
            super.setTitle(title);
    }

    @Override
    public void setSubtitle(CharSequence subtitle) {
        final TextView subtitleView = (TextView) findViewById(mSubtitleViewId);
        if (subtitleView != null) {
            subtitleView.setText(subtitle);
            subtitleView.setVisibility(TextUtils.isEmpty(subtitle) ? View.GONE : View.VISIBLE);
        } else
            super.setSubtitle(subtitle);
    }

    /**
     * {@inheritDoc}
     */
    public void setNavigationIcon(@Nullable Drawable icon) {
        final TextView navView = (TextView) findViewById(mNavigationViewId);
        if (navView != null) {
            mNavigationIcon = icon;
//            navView.setCompoundDrawables(mNavigationIcon, null, null, null);
            navView.setVisibility(mNavigationIcon != null ? View.VISIBLE : View.GONE);
        } else
            super.setNavigationIcon(icon);
    }

    /**
     * {@inheritDoc}
     */
    @Nullable
    public Drawable getNavigationIcon() {
        final TextView navView = (TextView) findViewById(mNavigationViewId);
        if (navView != null) {
            if (navView.getVisibility() == View.GONE)
                return null;
            return mNavigationIcon;
        }
        return super.getNavigationIcon();
    }

    /**
     * {@inheritDoc}
     */
    @Nullable
    public CharSequence getNavigationContentDescription() {
        final View navView = findViewById(mNavigationViewId);
        if (navView != null) {
            if (navView.getVisibility() == View.GONE)
                return null;
            return navView.getContentDescription();
        }
        return super.getNavigationContentDescription();
    }

    /**
     * {@inheritDoc}
     */
    public void setNavigationOnClickListener(OnClickListener listener) {
        final View navView = findViewById(mNavigationViewId);
        if (navView != null) {
            navView.setOnClickListener(listener);
        } else
            super.setNavigationOnClickListener(listener);
    }
}