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[英]Cannot resolve method 'findViewById(int)' in @Nullable fragment
[英]Cannot resolve 'findViewById' method in Fragment RecyclerView
我是 android 工作室的新手,我試圖在 Fragment 上創建 RecyclerView。 我正在關注教程,但我仍然收到消息“無法解析”findViewById
我試過做:
RecyclerView recyclerView = (RecyclerView)getView().findViewById(R.id.recyclerView);
但最終收到錯誤:
Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
這是代碼:
package com.example.app;
import android.os.Bundle;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class Articles extends Fragment {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
NewsList[] myListData = new NewsList[] {
new NewsList("Article 1", "Some Author"),
new NewsList("Article2", "Some Author"),
new NewsList("Article3", "Some Author"),
};
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
NewsAdapter adapter = new NewsAdapter(myListData);
recyclerView.setHasFixedSize(true);
recyclerView.setAdapter(adapter);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_create, container, false);
}
}
我該如何解決這個問題?
您的視圖尚未膨脹,這就是找不到它的原因。 將您的代碼從onCreate
移動到onViewCreated
片段生命周期。
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
// your view is discoverable here
RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
}
添加這些變量:
View root;
RecyclerView recyclerView;
將您的 onCreateView 更改為:
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
root = inflater.inflate(R.layout.fragment_profile, container, false);
recyclerView = root.findViewById(R.id.recyclerView);
return root;
}
最后 - 確保您的 XML 文件中的 recyclerview 具有以下內容:
android:id="@+id/recyclerView"
對於您的示例,您的列表 (myListDatae) 必須作為字段變量位於 NewsAdapter class 內。
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