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findViewById in Fragment

由 梦想的初衷 提交于 2019-11-25 22:55:58

问题


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.


回答1:


Use getView() or the View parameter from implementing the onViewCreated method. It returns the root view for the fragment (the one returned by onCreateView() method). With this you can call 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);

As getView() works only after onCreateView(), you can't use it inside onCreate() or onCreateView() methods of the fragment .




回答2:


You need to inflate the Fragment's view and call findViewById() on the View it returns.

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;
}



回答3:


Inside Fragment class you will get onViewCreated() override method where you should always initialize your views as in this method you get view object using which you can find your views like :

@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);
}

Always remember in case of Fragment that onViewCreated() method will not called automatically if you are returning null or super.onCreateView() from onCreateView() method. It will be called by default in case of ListFragment as ListFragment return FrameLayout by default.

Note: you can get the fragment view anywhere in the class by using getView() once onCreateView() has been executed successfully. i.e.

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



回答4:


I realise this is an old question, but the prevailing answer leaves something to be desired.

The question is not clear what is required of imageView - are we passing it back as the view, or merely saving a reference for later?

Either way, if the ImageView is coming from the inflated layout, the correct way to do this would be:

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;
    }
}



回答5:


Get first the fragment view and then get from this view your 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;
}



回答6:


You could also do it in the onActivityCreated Method. 

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

Like they do here: http://developer.android.com/reference/android/app/Fragment.html (deprecated in API level 28)

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

and

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

are possible.




回答7:


getView() will give the root view

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



回答8:


You can override onViewCreated() which is called right after all views had been inflated. It's the right place to fill in your Fragment's member View variables. Here's an example:

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);
    }
}



回答9:


The method getView() wont work on fragments outside OnCreate and similar methods.

You have two ways, pass the view to the function on the oncreate (what means you can only run your functions when the view is being created) or set the view as a variable:

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);
}



回答10:


1) first inflate layout of Fragment then you can use findviewbyId .

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



回答11:


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



回答12:


Use 

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

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

it will work




回答13:


agreed with calling findViewById() on the View.

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;
}



回答14:


Note :

From API Level 26, you also don't need to specifically cast the result of findViewById as it uses inference for its return type.

So now you can simply do,

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;
}



回答15:


According to the documentation on API level 11

Reference, in Back Stack http://developer.android.com/reference/android/app/Fragment.html

short code

/**
 * 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;
}



回答16:


Using getView() returns the view of the fragment, then you can call findViewById() to access any view element in the fragment view.




回答17:


Inside Fragment class you will get onViewCreated() override method where you should always initialize your views as in this method you get view object using which you can find your views like :

class MyFragment extends Fragment {
    private ImageView imageView;

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

    @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);
    }
}



回答18:


Try this it works for me 

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);
    }
}



回答19:


The best way to implement this is as follows: 

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
}

In this way, the rootView can be used for each control defined in the xml layout and the code is much cleaner in this way.

Hope this helps :)




回答20:


1) Declare your layout file. 

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

2)Then, get the id of your view 

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



回答21:


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.




回答22:


Try This:

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

return v;



回答23:


try

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;
}



回答24:


You can call findViewById() with the Activity Object you get inside your public void onAttach(Activity activity) method inside your Fragment.

Save the Activity into a variable for example:

In the Fragment class: private Activity mainActivity; In the onAttach() method: this.mainActivity=activity;

Finally execute every findViewById through the vairable: mainActivity.findViewById(R.id.TextView);




回答25:


There is one more method called onViewCreated.

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



回答26:


Inside onCreateView method

1) first you have to inflate the layout/view you want to add eg. LinearLayout

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

2) Then you can find your imageView id from layout

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

3)return the inflated layout

return ll;



回答27:


You have to inflate the view

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
}}



回答28:


In fragments we need a view of that window so that we make a onCreateView of this Fragment.

Then get the view and use it to access each and every view id of that view elements..

  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;
        }
    }



回答29:


Layout inflater comes into picture here. Layout inflater is a class that make us able to use the XML views in java code. So you can inflate the root xml view in variable v with the following code. And then using v, you can find the child views of the root view v.

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;
    }
}



回答30:


The easiest way to use such things is to use butterknife By this you can add as many Onclciklisteners just by @OnClick() as described below:

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;
    }
}


来源：https://stackoverflow.com/questions/6495898/findviewbyid-in-fragment

标签
android
android-fragments
android-imageview
findviewbyid
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