android - RecyclerView 致命异常 :main

Question

有人可以帮助我知道是什么导致了我的 recyclerview 中的这个错误我已经尝试更改变量名称

Adapter1.java:48

但它仍然给我同样的错误。

java.lang.NullPointerException
at ke.co.clickaway.squirrel.clickawaytechnologies.adpter.Adapter1.getItemCount(Adapter1.java:48)

代码如下

public class MainActivity extends AppCompatActivity {
    Toolbar toolbar;
    ArrayList<DataList> list;
//in the onCreate Bundle
RecyclerView rview=(RecyclerView) findViewById(R.id.rview);
        Adapter1 adapter1=new Adapter1(this,list);
        rview.setAdapter(adapter1);
        StaggeredGridLayoutManager lm=new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL);
        rview.setLayoutManager(lm);

信息类

public class DataList {
    public int imageView;
    public String title;

    public static List<DataList> getData(){
        ArrayList<DataList> mList=new ArrayList<>();
        int[] imag={R.drawable.web_ic,R.drawable.palette_ic,R.drawable.pencil,R.drawable.sware_ic,R.drawable.phone_ic};
        String[] lable={"Web Development","Branding","Graphic Design","Systems","Mobile Apps"};
        for(int i=0;i<lable.length&& i<imag.length;i++){
            DataList dataList=new DataList();
            dataList.title=lable[i];
            dataList.imageView=imag[i];
            mList.add(dataList);
        }
        return mList;
    }
}

还有我的适配器

public class Adapter1 extends RecyclerView.Adapter<Adapter1.ViewHolder> {
    private List<DataList> mList;
    private Context mContext;
    public Adapter1(Context context,List<DataList> list){
          mList=list;
          mContext=context;
    }
    private Context getContext(){
        return mContext;
    }
    @Override
    public Adapter1.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        Context context=parent.getContext();
        LayoutInflater inflater=LayoutInflater.from(context);
        View customView=inflater.inflate(R.layout.custom_view,parent,false);
        ViewHolder viewHolder=new ViewHolder(customView);
        return viewHolder;

    }

    @Override
    public void onBindViewHolder(Adapter1.ViewHolder holder, int position) {
         DataList dataList=mList.get(position);
         holder.imag.setImageResource(dataList.imageView);
         holder.lable.setText(dataList.title);
         }

    @Override
    public int getItemCount() {
        return mList.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        public ImageView imag;
        public TextView lable;

        public ViewHolder(View itemView) {
            super(itemView);
            imag= (ImageView)itemView.findViewById(R.id.imageView1);
            lable=(TextView)itemView.findViewById(R.id.textView1);
        }
    }
}

我的自定义 View

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/imageView1"
        android:layout_gravity="center"
        android:layout_width="88dp"
        android:layout_height="88dp"
        android:layout_marginTop="5dp"
        android:layout_marginBottom="5dp"
        android:src="@drawable/one" />
    <TextView
        android:id="@+id/textView1"
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="15dp"
        android:layout_marginTop="5dp"
        android:layout_marginBottom="5dp"
        android:text="dummy Text" />
</LinearLayout>

activty_main.xml 中的 RecyclerView fragment

<android.support.v7.widget.RecyclerView
        android:layout_below="@id/appbarlayout"
        android:id="@+id/rview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

Answer 1

列表 为空。因此，在创建适配器或将适配器中的 getItemCount() 方法更改为此之前初始化列表:

@Override
public int getItemCount() {
    return mList == null ? 0 : mList.size();
}