recyclerView學習筆記

在使用recyclerView結合StaggeredGridLayoutManager實現瀑布流時遇到item間隔不一致的問題。

我的問題出現在onCreateViewHolder中，在創建ViewHolder時，使用的inflate方法造成的。

inflate方法有兩種形式，一個是兩個參數

/**
 * Inflate a new view hierarchy from the specified xml resource. Throws
 * {@link InflateException} if there is an error.
 * 
 * @param resource ID for an XML layout resource to load (e.g.,
 *        <code>R.layout.main_page</code>)
 * @param root Optional view to be the parent of the generated hierarchy.
 * @return The root View of the inflated hierarchy. If root was supplied,
 *         this is the root View; otherwise it is the root of the inflated
 *         XML file.
 */
public View inflate(@LayoutRes int resource, @Nullable ViewGroup root) {
    return inflate(resource, root, root != null);
}

一個是三個參數的

/**
 * Inflate a new view hierarchy from the specified xml resource. Throws
 * {@link InflateException} if there is an error.
 * 
 * @param resource ID for an XML layout resource to load (e.g.,
 *        <code>R.layout.main_page</code>)
 * @param root Optional view to be the parent of the generated hierarchy (if
 *        <em>attachToRoot</em> is true), or else simply an object that
 *        provides a set of LayoutParams values for root of the returned
 *        hierarchy (if <em>attachToRoot</em> is false.)
 * @param attachToRoot Whether the inflated hierarchy should be attached to
 *        the root parameter? If false, root is only used to create the
 *        correct subclass of LayoutParams for the root view in the XML.
 * @return The root View of the inflated hierarchy. If root was supplied and
 *         attachToRoot is true, this is root; otherwise it is the root of
 *         the inflated XML file.
 */
public View inflate(@LayoutRes int resource, @Nullable ViewGroup root, boolean attachToRoot) {
    final Resources res = getContext().getResources();
    if (DEBUG) {
        Log.d(TAG, "INFLATING from resource: \"" + res.getResourceName(resource) + "\" ("
                + Integer.toHexString(resource) + ")");
    }

    final XmlResourceParser parser = res.getLayout(resource);
    try {
        return inflate(parser, root, attachToRoot);
    } finally {
        parser.close();
    }
}

這兩個inflate都共有一個參數  root 參數，

root：需要附加到resource資源文件的根控件，什麼意思呢，就是inflate()會返回一個View對象，

如果第三個參數attachToRoot爲true，

就將這個root作爲根對象返回，

否則僅僅將這個root對象的LayoutParams屬性附加到resource對象的根佈局對象上，

也就是佈局文件resource的最外層的View上，比如是一個LinearLayout或者其它的Layout對象

如果root不爲空的話，那麼root的LayoutParams屬性會附加到resource對象的根佈局對象上，這就容易導致item 間距不一，所以

在創建ViewHolder的時候第二個參數爲空。

上述如不正確，請指正！