java - 从 android studio 中的 onCreateview 调用新方法中的 View

Question

我试图用我的新方法从我的充气机中调用“ View ”，但它不起作用，它说未解决。如果我将 setUpRecyclerView 下的整个代码移动到 onCreateView 中，它就可以工作。有没有办法让它按原样工作，这样我就可以保持 onCreatView 整洁？所有代码都在一个 fragment 中。我也尝试过使用 getView.findViewById 但这也不起作用。

'''

package com.example.hostapp;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.firebase.ui.firestore.FirestoreRecyclerOptions;
import com.google.firebase.firestore.CollectionReference;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.Query;

public class HomeFragment extends Fragment {

    private FirebaseFirestore db = FirebaseFirestore.getInstance();
    private CollectionReference categoryref = db.collection("categories");
    private categoryCardAdapter adapter;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_home, container, false);




        return view;
    }

    public void setUpRecyclerView (){
        Query query = categoryref.orderBy("name",Query.Direction.DESCENDING);

        FirestoreRecyclerOptions<categoryCard> options = new FirestoreRecyclerOptions.Builder<categoryCard>()
                .setQuery(query, categoryCard.class)
                .build();

        adapter = new categoryCardAdapter(options);

        RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.recycler_category);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this.getActivity()));
        recyclerView.setAdapter(adapter);
    }

    @Override
    public void onStart() {
        super.onStart();
        adapter.startListening();
    }

    @Override
    public void onStop() {
        super.onStop();
        adapter.stopListening();
    }
}

'''

这是有效的代码:

package com.example.hostapp;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.firebase.ui.firestore.FirestoreRecyclerOptions;
import com.google.firebase.firestore.CollectionReference;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.Query;

public class HomeFragment extends Fragment {

    private FirebaseFirestore db = FirebaseFirestore.getInstance();
    private CollectionReference categoryref = db.collection("categories");
    private categoryCardAdapter adapter;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_home, container, false);


        Query query = categoryref.orderBy("name",Query.Direction.DESCENDING);

        FirestoreRecyclerOptions<categoryCard> options = new FirestoreRecyclerOptions.Builder<categoryCard>()
                .setQuery(query, categoryCard.class)
                .build();

        adapter = new categoryCardAdapter(options);

        **RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.recycler_category);**
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this.getActivity()));
        recyclerView.setAdapter(adapter);

        return view;
    }

    public void setUpRecyclerView (){

    }

    @Override
    public void onStart() {
        super.onStart();
        adapter.startListening();
    }

    @Override
    public void onStop() {
        super.onStop();
        adapter.stopListening();
    }
}

Answer 1

您没有在第一个代码示例中调用 setupRecyclerView() 方法。您可以在返回 View 之前从 createView() 方法调用它，也可以从 onViewCreated() 方法调用该方法。我更喜欢第二种选择。