ListView findViewById返回null [英] ListView findViewById returning null

问题描述

我不使用ListActivity，因为我想扩展FragmentActivity.相反，我尝试使用:

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);

不幸的是lv为空.

在我的xml中，我有:

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>

我还尝试为列表视图使用不同的Android ID，例如使用ListActivity时必须使用的ID，但始终为Null.

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.

我试图在调用setContentView之前调用findViewById.首先调用setContentView对其进行修复.

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

推荐答案

正如JRaymond不久前在评论中提到的那样，在使用findViewById之前，我需要先调用setContentView.

As JRaymond mentioned in a comment awhile ago, I needed to call setContentView before using findViewById.

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