ListView findViewById返回null

Question

I'm not using a ListActivity because I want to extend FragmentActivity. Instead I'm trying to use:

ListView lv = (ListView) findViewById(R.id.mainListView);

Unfortunately lv is null.

In my xml I have:

 <ListView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/mainListView"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1" >
</ListView>

I've also tried using different android id's for the list view such as the one you have to use when you use ListActivity, but it's always Null.

Edit: I was trying to call findViewById before calling setContentView. Calling setContentView first fixed it.

Answer 1

正如JRaymond之前在评论中提到的那样，我需要在使用findViewById之前调用setContentView。

Answer 2

您应该将setContentView放在findViewById之上。

Answer 3

尝试：

ListView lv = (ListView) view.findViewById(R.id.mainListView);

Answer 4

this may helps you

 xmlns:android="http://schemas.android.com/apk/res/android"

remove it from your Listview in xml and use like

<ListView
    android:id="@+id/mainListView"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1" >
</ListView>