android - Android Fragment Tutorial's code not clear

Question

I'm brushing up on my Fragments knowledge following the official tutorial from android developers website; there is a statement into the demo code that doesn't sound clear to me

FragmentTransaction ft = getFragmentManager().beginTransaction();
if (index == 0) {
    ft.replace(R.id.details, details);
} else {
    ft.replace(R.id.a_item, details);
}

I think I can understand the logic behind the code, but can't figure out where is that item with id = a_item; it doesn't seem to be declared anywhere and obviously the demo app doesn't work.

Can you help me to better understand that piece of code? Thanks in advance

Answer 1

• R.id.details指ViewGroup您要在其中插入片段（或替换片段）的内部。

• details指应该插入/替换的片段的实例ViewGroup

笔记：

• 不要忘记打电话transaction.commit()给实际

• 这不适用于使用片段标记直接插入 XML 的片段。您只能替换从 Java 代码中插入的片段。