为什么 FindViewById 不出来？如果我自己写，它会变成红色的错误

问题描述

为什么 FindViewById 不起作用？如果我输入 findView ...，则 findViewById 不会出现，如果我自己输入，它会写错误。我的代码（片段）：

public class BiografiyaFragment extends Fragment {

    private static final String ARG_ParaM1 = "param1";
    private static final String ARG_ParaM2 = "param2";
    private String mParam1;
    private String mParam2;

    public BiografiyaFragment() {
    }

    public static BiografiyaFragment newInstance(String param1,String param2) {
        BiografiyaFragment fragment = new BiografiyaFragment();
        Bundle args = new Bundle();
        args.putString(ARG_ParaM1,param1);
        args.putString(ARG_ParaM2,param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_ParaM1);
            mParam2 = getArguments().getString(ARG_ParaM2);
        }
    }

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

screenshot

解决方法

这是一个片段。因此，您必须在 View 方法中创建一个 onCreateView 类的对象。因此，onCreateView 中的代码将是，

@Override
public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
        View view=inflater.inflate(R.layout.fragment_biografiya,container,false);
        // I am assuming a textview here....
        TextView textView=view.findViewById(R.id.textView);
        return view;
}

,

以现代方式，最好的解决方案是使用 ViewBinding。

使用步骤

build.gradle

   android {
        ...
        buildFeatures {
            viewBinding true
        } 
}

您的代码

public class BiografiyaFragment extends Fragment {

    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";
    private String mParam1;
    private String mParam2;
    private BiografiyaBinding binding; // new added.


    public BiografiyaFragment() {
    }

    public static BiografiyaFragment newInstance(String param1,String param2) {
        BiografiyaFragment fragment = new BiografiyaFragment();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1,param1);
        args.putString(ARG_PARAM2,param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater,Bundle savedInstanceState) {
        binding = BiografiyaBinding.inflate(inflater,false); // Added
        return binding.getRoot();
}

@Override
    public void onViewCreated(@NonNull View view,@Nullable Bundle savedInstanceState) {
       // Sample 
       //binding.sampleViewIdName...
    }

}

,

在片段中，你必须通过与视图关联来调用这个函数 喜欢

view.findViewById()

在这里，视图是

View view = inflater.inflate(R.layout.fragment_biografiya,false);