findViewById（）返回null，为什么呢？ [英] findViewById() returns Null, Why?

问题描述

我有一个是通过findViewById搜索并保存返回NULL一个TextView。我有一个指向包含比我的TextView的另一个布局类的OnCreate一个的setContentView。如何使它返回返回null好吗？

I have a textView which is searched by findViewById and that keeps returning Null. I have a setContentView on the onCreate of the class that points to a layout other than the one containing my textView. How to make it return none null please ?

下面是我的活动和两个XML文件：

below is my activity and the two xml files :

activity_process.xml：

activity_process.xml :

   <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:id="@+id/content_process"
      android:orientation="vertical"
      android:layout_width="match_parent"
      android:layout_height="match_parent"/>

<TextView
                android:id="@+id/enrollmenttype"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:padding="10dp"
                android:text="@string/enrollmenttype_value" />

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_process);

，因为它是一个隐藏的活动我不能编辑activity_process.xml。我需要找到一个方法来过来这一切。

I can't edit the activity_process.xml since it is a hidden activity. I need to find a way to come over all this.

推荐答案

该方法 findViewById 会给你只是你与<$ C设置布局以下儿童的意见$ C>的setContentView 。为什么你想从你的活动不使用布局得到了的TextView ？这是错误的各种方式。

The method findViewById will give you only views that are children under the layout you set with setContentView. Why are you trying to get a TextView from a layout that your activity doesn't use? That is wrong in all sorts of ways.

所以为了让它工作，你必须把那个的TextView 在 activity_process.xml 是这样的：

So in order for it to work, you have to put that TextView in activity_process.xml like this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/content_process"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:layout_height="match_parent">
  <TextView
            android:id="@+id/enrollmenttype"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:padding="10dp"
            android:text="@string/enrollmenttype_value">
  </TextView>
 </LinearLayout>

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