Toolbar.java

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

        // Need to use getContext() here so that we use the themed context
        final TintTypedArray a = TintTypedArray.obtainStyledAttributes(getContext(), attrs,
                R.styleable.Toolbar, defStyleAttr, 0);

        mTitleTextAppearance = a.getResourceId(R.styleable.Toolbar_titleTextAppearance, 0);
        mSubtitleTextAppearance = a.getResourceId(R.styleable.Toolbar_subtitleTextAppearance, 0);
        mGravity = a.getInteger(R.styleable.Toolbar_android_gravity, mGravity);
        mButtonGravity = Gravity.TOP;
        mTitleMarginStart = mTitleMarginEnd = mTitleMarginTop = mTitleMarginBottom =
                a.getDimensionPixelOffset(R.styleable.Toolbar_titleMargins, 0);

        final int marginStart = a.getDimensionPixelOffset(R.styleable.Toolbar_titleMarginStart, -1);
        if (marginStart >= 0) {
            mTitleMarginStart = marginStart;
        }

        final int marginEnd = a.getDimensionPixelOffset(R.styleable.Toolbar_titleMarginEnd, -1);
        if (marginEnd >= 0) {
            mTitleMarginEnd = marginEnd;
        }

        final int marginTop = a.getDimensionPixelOffset(R.styleable.Toolbar_titleMarginTop, -1);
        if (marginTop >= 0) {
            mTitleMarginTop = marginTop;
        }

        final int marginBottom = a.getDimensionPixelOffset(R.styleable.Toolbar_titleMarginBottom,
                -1);
        if (marginBottom >= 0) {
            mTitleMarginBottom = marginBottom;
        }

        mMaxButtonHeight = a.getDimensionPixelSize(R.styleable.Toolbar_maxButtonHeight, -1);

        final int contentInsetStart =
                a.getDimensionPixelOffset(R.styleable.Toolbar_contentInsetStart,
                        RtlSpacingHelper.UNDEFINED);
        final int contentInsetEnd =
                a.getDimensionPixelOffset(R.styleable.Toolbar_contentInsetEnd,
                        RtlSpacingHelper.UNDEFINED);
        final int contentInsetLeft =
                a.getDimensionPixelSize(R.styleable.Toolbar_contentInsetLeft, 0);
        final int contentInsetRight =
                a.getDimensionPixelSize(R.styleable.Toolbar_contentInsetRight, 0);

        mContentInsets.setAbsolute(contentInsetLeft, contentInsetRight);

        if (contentInsetStart != RtlSpacingHelper.UNDEFINED ||
                contentInsetEnd != RtlSpacingHelper.UNDEFINED) {
            mContentInsets.setRelative(contentInsetStart, contentInsetEnd);
        }

        mCollapseIcon = a.getDrawable(R.styleable.Toolbar_collapseIcon);
        mCollapseDescription = a.getText(R.styleable.Toolbar_collapseContentDescription);

        final CharSequence title = a.getText(R.styleable.Toolbar_title);
        if (!TextUtils.isEmpty(title)) {
            setTitle(title);
        }

        final CharSequence subtitle = a.getText(R.styleable.Toolbar_subtitle);
        if (!TextUtils.isEmpty(subtitle)) {
            setSubtitle(subtitle);
        }
        // Set the default context, since setPopupTheme() may be a no-op.
        mPopupContext = getContext();
        setPopupTheme(a.getResourceId(R.styleable.Toolbar_popupTheme, 0));

        final Drawable navIcon = a.getDrawable(R.styleable.Toolbar_navigationIcon);
        if (navIcon != null) {
            setNavigationIcon(navIcon);
        }
        final CharSequence navDesc = a.getText(R.styleable.Toolbar_navigationContentDescription);
        if (!TextUtils.isEmpty(navDesc)) {
            setNavigationContentDescription(navDesc);
        }

        a.recycle();

        // Keep the TintManager in case we need it later
        mTintManager = a.getTintManager();
    }