java - Android:RecyclerView 空指针异常

Question

我已经创建了回收器 View ，并且已在 Gradle 文件中导入了所有必要的依赖项。我的目标 SDK 是 29.所以我所有的依赖都是 androidx在我的布局文件中，我还创建了“list”的 id，但我不知道为什么它显示错误。预先感谢您。

package com.napps.wallpaper;

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;

public class fragment_wallpaper extends Fragment {

    RecyclerView recyclerView;
    RecyclerView.LayoutManager layoutManager;
    RecyclerView.Adapter adapter;
    View view;

    public fragment_wallpaper(){

    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

        View view= inflater.inflate(R.layout.fragment_wallpaper,container,false);
        return  view;

    }


    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);


        recyclerView=view.findViewById(R.id.list); //this where i am getting error
        recyclerView.setHasFixedSize(true);

        layoutManager=new LinearLayoutManager(this.getActivity());
        recyclerView.setLayoutManager(layoutManager);

        adapter=new imageAdapter(this.getActivity(),array_class.arrayurl);
        recyclerView.setAdapter(adapter);

    }

}

Answer 1

试试这个
基本上，您没有初始化 View ，而是创建了一个导致麻烦的新变量。希望能帮助到你。快乐编码:)

        @Nullable
        @Override
        public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

            view= inflater.inflate(R.layout.fragment_wallpaper,container,false);
            return  view;

        }