onFinishInflate() 跟踪

基于android 4.4.1:

    /**
     * Finalize inflating a view from XML.  This is called as the last phase
     * of inflation, after all child views have been added.
     *
     * <p>Even if the subclass overrides onFinishInflate, they should always be
     * sure to call the super method, so that we get called.
     */
    protected void onFinishInflate() {
    }

在layoutInflate类中， inflate(XmlPullParser parser, ViewGroup root, boolean attachToRoot) 会调用到 rInflate(XmlPullParser parser, View parent, final AttributeSet attrs, boolean finishInflate)，

/**
     * Recursive method used to descend down the xml hierarchy and instantiate
     * views, instantiate their children, and then call onFinishInflate().
     */
    void rInflate(XmlPullParser parser, View parent, final AttributeSet attrs,
            boolean finishInflate) throws XmlPullParserException, IOException

r代表递归，该方法将以递归向下（其实就是DFS）的顺序实例化view，在将某个view的全部子孙view都实例化完以后，会调用该view的onFinishInflate()。

只有子view全部都实例化以后，我们在该view的onFinishInflate()函数中才能使用findViewById(id)找到id对应的子view实例。