android - findViewById in Fragment

Question

I am trying to create an ImageView in a Fragment which will refer to the ImageView element which I have created in the XML for the Fragment. However, the findViewById method only works if I extend an Activity class. Is there anyway of which I can use it in Fragment as well?

public class TestClass extends Fragment {
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        ImageView imageView = (ImageView)findViewById(R.id.my_image);
        return inflater.inflate(R.layout.testclassfragment, container, false);
    }
}

The findViewById method has an error on it which states that the method is undefined.

score 1548 · Accepted Answer

使用getView()或实现该 onViewCreated方法的 View 参数。它返回片段的根视图（onCreateView()方法返回的那个）。有了这个，你可以调用findViewById().

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    ImageView imageView = (ImageView) getView().findViewById(R.id.foo);
    // or  (ImageView) view.findViewById(R.id.foo);

由于getView()仅在之后起作用onCreateView()，您不能onCreate()onCreateView()在片段的内部或方法中使用它。

score 650 · Accepted Answer

您需要膨胀 Fragment 的视图并调用findViewById()它View返回。

public View onCreateView(LayoutInflater inflater, 
                         ViewGroup container, 
                         Bundle savedInstanceState) {
     View view = inflater.inflate(R.layout.testclassfragment, container, false);
     ImageView imageView = (ImageView) view.findViewById(R.id.my_image);
     return view;
}

score 148 · Accepted Answer

在Fragment类中，您将获得onViewCreated()覆盖方法，您应该始终初始化您的视图，因为在此方法中您将获得视图对象，您可以使用它找到您的视图，如：

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    view.findViewById(R.id.yourId).setOnClickListener(this);

    // or
    getActivity().findViewById(R.id.yourId).setOnClickListener(this);
}

永远记住，在 Fragment 的情况下，如果您返回 null 或from方法，则该onViewCreated()方法不会自动调用。在默认返回的情况下会默认调用它。super.onCreateView()onCreateView()ListFragmentListFragmentFrameLayout

注意：你可以在类中的任何地方通过使用getView()一次onCreateView()成功执行来获取片段视图。IE

getView().findViewById("your view id");

score 68 · Accepted Answer

我意识到这是一个老问题，但普遍的答案还有待改进。

问题尚不清楚需要什么imageView- 我们是将其作为视图传递回来，还是只是保存参考以供以后使用？

无论哪种方式，如果ImageView来自膨胀的布局，正确的方法是：

public class TestClass extends Fragment {
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.testclassfragment, container, false);
        ImageView imageView = (ImageView)v.findViewById(R.id.my_image);
        return v;
    }
}

score 52 · Accepted Answer

首先获取片段视图，然后从该视图获取您的 ImageView。

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.testclassfragment, container, false);
    ImageView imageView = (ImageView) view.findViewById(R.id.my_image);
    return view;
}

score 29 · Accepted Answer

您也可以在onActivityCreated方法中执行此操作。

public void onActivityCreated(Bundle savedInstanceState) { 
      super.onActivityCreated(savedInstanceState);
}

就像他们在这里做的那样：http: //developer.android.com/reference/android/app/Fragment.html （在 API 级别 28 中已弃用）

getView().findViewById(R.id.foo);

和

getActivity().findViewById(R.id.foo);

是可能的。

score 29 · Accepted Answer

在Fragment类内部，我们得到onViewCreated()了覆盖方法，我们应该始终初始化我们的视图，因为在这个方法中我们得到了view对象。使用这个对象，我们可以找到如下视图：

class MyFragment extends Fragment {
    private ImageView imageView;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.my_fragment_layout, container, false);
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        //initialize your view here for use view.findViewById("your view id")
        imageView = (ImageView) view.findViewById(R.id.my_image);
    }
}

score 20 · Accepted Answer

20

getView()将给出根视图

View v = getView().findViewByID(R.id.x);

于 2014-09-03T12:41:44.007 回答

score 18 · Accepted Answer

您可以覆盖 onViewCreated() ，它在所有视图都被膨胀后立即调用。这是填写 Fragment 成员View变量的正确位置。这是一个例子：

class GalleryFragment extends Fragment {
    private Gallery gallery;

    (...)

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        gallery = (Gallery) view.findViewById(R.id.gallery);
        gallery.setAdapter(adapter);
        super.onViewCreated(view, savedInstanceState);
    }
}

score 16 · Accepted Answer

getView()方法不适用于 OnCreate 和类似方法之外的片段。

您有两种方法，将视图传递给 oncreate 上的函数（这意味着您只能在创建视图时运行函数）或将视图设置为变量：

private View rootView;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
    Bundle savedInstanceState) {
    rootView = inflater.inflate(R.layout.fragment_contatos, container, false);
}

public void doSomething () {
    ImageView thumbnail = (ImageView) rootView.findViewById(R.id.someId);
}

score 15 · Accepted Answer

1）首先膨胀片段的布局，然后你可以使用 findviewbyId 。

View view = inflater.inflate(R.layout.testclassfragment, container, false);
             ImageView imageView = (ImageView) view.findViewById(R.id.my_image);
             return view;

score 10 · Accepted Answer

EditText name = (EditText) getView().findViewById(R.id.editText1);
EditText add = (EditText) getView().findViewById(R.id.editText2);

score 10 · Accepted Answer

同意调用findViewById()视图。

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View V = inflater.inflate(R.layout.testclassfragment, container, false);
    ImageView imageView = (ImageView) V.findViewById(R.id.my_image);

    return V;
}

score 10 · Accepted Answer

笔记：

从 API 级别 26 开始，您也不需要专门转换 findViewById 的结果，因为它对其返回类型使用推理。

所以现在你可以简单地做，

public View onCreateView(LayoutInflater inflater, 
                         ViewGroup container, 
                         Bundle savedInstanceState) {
     View view = inflater.inflate(R.layout.testclassfragment, container, false);
     ImageView imageView =  view.findViewById(R.id.my_image); //without casting the return type
     return view;
}

score 9 · Accepted Answer

利用

imagebutton = (ImageButton) getActivity().findViewById(R.id.imagebutton1);

imageview = (ImageView) getActivity().findViewById(R.id.imageview1);

它会起作用的

score 8 · Accepted Answer

根据 API 级别 11 的文档

参考，在 Back Stack http://developer.android.com/reference/android/app/Fragment.html

短代码

/**
 * The Fragment's UI is just a simple text view showing its
 * instance number.
 */
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.hello_world, container, false);
    View tv = v.findViewById(R.id.text);
    ((TextView)tv).setText("Fragment #" + mNum);
    tv.setBackgroundDrawable(getResources().getDrawable(android.R.drawable.gallery_thumb));
    return v;
}

score 8 · Accepted Answer

usinggetView()返回片段的视图，然后您可以调用findViewById()以访问片段视图中的任何视图元素。

score 8 · Accepted Answer

试试这个它对我有用

public class TestClass extends Fragment {
    private ImageView imageView;

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.testclassfragment, container, false);
        findViews(view);
        return view;
    }

    private void findViews(View view) {
        imageView = (ImageView) view.findViewById(R.id.my_image);
    }
}

score 5 · Accepted Answer

实现这一点的最佳方法如下：

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

rootView = inflater.inflate(R.layout.testclassfragment, container, false);
        ImageView imageView = (ImageView) rootView.findViewById(R.id.my_image);
        return rootView
}

这样，xml布局中定义的每一个控件都可以使用rootView，这样代码就干净多了。

希望这可以帮助：）

score 5 · Accepted Answer

1）声明你的布局文件。

public View onCreateView(LayoutInflater inflater,ViewGroup container, 
                                 Bundle savedInstanceState) {
    return inflate(R.layout.myfragment, container, false);
}

2）然后，获取您的视图的ID

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    TextView nameView = (TextView) view.findViewById(R.id.textview1);
}

score 4 · Accepted Answer

Use gradle skeleton plugin, it will automatically generate the view holder classes with the reference to your layout.

public class TestClass extends Fragment {
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        MyLayout myLayout = new MyLayout(inflater, container, false);
        myLayout.myImage.setImageResource(R.drawable.myImage);
        return myLayout.view;
    }
}

Now assuming you had an ImageView declared in your my_layout.xml file, it will automatically generate myLayout class for you.

score 4 · Accepted Answer

尝试这个：

View v = inflater.inflate(R.layout.testclassfragment, container, false);
ImageView img = (ImageView) v.findViewById(R.id.my_image);

return v;

score 4 · Accepted Answer

尝试

private View myFragmentView;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) 
{
myFragmentView = inflater.inflate(R.layout.myLayoutId, container, false);
myView = myFragmentView.findViewById(R.id.myIdTag)
return myFragmentView;
}

score 3 · Accepted Answer

您可以使用您内部findViewById()的活动对象进行调用public void onAttach(Activity activity)使用在Fragment 中

将 Activity 保存到变量中，例如：

在片段类中： private Activity mainActivity; 在onAttach()方法中： this.mainActivity=activity;

最后通过变量执行每个 findViewById： mainActivity.findViewById(R.id.TextView);

score 3 · Accepted Answer

我喜欢一切都井井有条。你可以这样做。

首先初始化视图

private ImageView imageView;

然后覆盖 OnViewCreated

@Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        findViews(view);
    }

然后添加一个void方法来查找视图

private void findViews(View v) {
    imageView = v.findViewById(R.id.img);
}

score 3 · Accepted Answer

还有一种称为 onViewCreated 的方法。

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    ImageView imageView = (ImageView) view.findViewById(R.id.imageview1);
}

score 2 · Accepted Answer

//here you can do it by
   public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState)
  {
    // Inflate the layout for this fragment
    final View view =  inflater.inflate(R.layout.fragment_apple, container, 
 false);
    ist = view.findViewById(R.id.linearLink);
    second = view.findViewById(R.id.linearPhone);
    return view;

score 2 · Accepted Answer

布局充气机在这里出现。Layout inflater 是一个使我们能够在 java 代码中使用 XML 视图的类。因此，您可以使用以下代码扩展变量 v 中的根 xml 视图。然后使用 v，可以找到根视图 v 的子视图。

public class TestClass extends Fragment {
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.testclassfragment, container, false);
    ImageView imageView = (ImageView)v.findViewById(R.id.my_image);
    return v;
    }
}

score 2 · Accepted Answer

在片段中，我们需要该窗口的视图，以便我们创建此片段的 onCreateView。

然后获取视图并使用它来访问该视图元素的每个视图 id..

  class Demo extends Fragment
    {
        @Override
        public View onCreateView(final LayoutInflater inflater,ViewGroup container, Bundle savedInstanceState)
        {
            View view =inflater.inflate(R.layout.demo_fragment, container,false);
            ImageView imageview=(ImageView)view.findViewById(R.id.imageview1);

            return view;
        }
    }

score 2 · Accepted Answer

getView()仅在 onCreateView()完成后才起作用，因此请从以下位置调用它onPostCreate()：

@Override
public void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    ImageView imageView = (ImageView) getView().findViewById(R.id.foo);
}

score 2 · Accepted Answer

onCreateView 方法内部

1）首先你必须膨胀你想要添加的布局/视图，例如。线性布局

LinearLayout ll = inflater.inflate(R.layout.testclassfragment, container, false);

2）然后你可以从布局中找到你的imageView id

ImageView imageView = (ImageView)ll.findViewById(R.id.my_image);

3）返回膨胀的布局

return ll;

score 2 · Accepted Answer

你必须给视图充气

public class TestClass extends Fragment {

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.testclassfragment, container, false);
    ImageView imageView = (ImageView)v.findViewById(R.id.my_image);
    return v
}}

score 1 · Accepted Answer

使用这些东西的最简单方法是使用黄油刀通过这种方式，您可以通过 @OnClick() 添加尽可能多的 Onclciklistener，如下所述：

public class TestClass extends Fragment {
    @BindView(R.id.my_image) ImageView imageView;
    @OnClick(R.id.my_image)
    public void my_image_click(){
        yourMethod();
    }
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view=inflater.inflate(R.layout.testclassfragment, container, false);
        ButterKnife.bind(getActivity,view);
        return view;
    }
}

score 1 · Accepted Answer

非常简单的做法：

 @Nullable
        @Override
        public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
            View fragmentView = inflater.inflate(R.layout.testclassfragment, container, false);
            ImageView imageView = (ImageView)fragmentView.findViewById(R.id.my_image);
            return fragmentView;
       }

score 0 · Accepted Answer

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
     View view = inflater.inflate(R.layout.testclassfragment, container, false);
     ImageView imageView = (ImageView) view.findViewById(R.id.my_image);
     return view;
}

请注意，如果您使用getView()它可能会导致的方法，nullPointerException因为它返回根视图，并且它将是onCreateView()方法后的一些视图。

score 0 · Accepted Answer

ImageView imageView;
public View onCreateView(LayoutInflater inflater, 
                     ViewGroup container, 
                     Bundle savedInstanceState) {
 View view = inflater.inflate(R.layout.testclassfragment, container, false);
 imageView = view.findViewById(R.id.my_image);
 return view;

}

score -3 · Accepted Answer

.commit() 之后的事务时间也可能导致此问题

我遇到了同样的问题（无法访问片段中的视图）。原因是，在 (FragmentTransaction) .commit()之后，视图没有在 UI 中激活。无法保证.commit() 之后的事务何时发生；它只是排队。所以我添加了一个 (FragmentManager) .executePendingTransactions()来强制完成事务。之后，引用视图按预期工作！

android - findViewById in Fragment

37 回答 37

.commit() 之后的事务时间也可能导致此问题

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