在片段中使用上下文

本文翻译自：Using context in a fragment

How can I get the context in a fragment? 如何获取片段中的上下文？

I need to use my database whose constructor takes in the context, but getApplicationContext() and FragmentClass.this don't work so what can I do? 我需要使用其构造函数接受上下文的数据库，但getApplicationContext()和FragmentClass.this不起作用，该怎么办？

Database constructor 数据库构造函数

public Database(Context ctx)
{
    this.context = ctx;
    DBHelper = new DatabaseHelper(context);
}

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#1楼

参考：https://stackoom.com/question/YTAy/在片段中使用上下文

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#2楼

To do as the answer above, you can override the onAttach method of fragment: 为此，您可以覆盖片段的onAttach方法：

public static class DummySectionFragment extends Fragment{
...
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        DBHelper = new DatabaseHelper(activity);
    }
}

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#3楼

The easiest and most precise way to get the context of the fragment that I found is to get it directly from the ViewGroup when you call onCreateView method at least here you are sure not to get null for getActivity() : 获取我发现的片段上下文的最简单，最精确的方法是，至少在这里，当您调用onCreateView方法时，直接从ViewGroup获取片段：请确保不会为getActivity()获得null：

public class Animal extends Fragment { 
  Context thiscontext;
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
  {
    thiscontext = container.getContext();

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#4楼

始终使用getActivity（）方法获取所附加活动的上下文，但始终要记住一件事：片段稍微不稳定，并且getActivity有时会返回null，因此，在获取上下文之前，请务必先检查片段的iwego（）方法getActivity() 。

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#5楼

Another alternative approach is: 另一种替代方法是：

You can get the context using: 您可以使用以下方式获取上下文：

getActivity().getApplicationContext();

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#6楼

@Override
public void onAttach(Activity activity) {
    // TODO Auto-generated method stub
    super.onAttach(activity);
    context=activity;
}