空指针异常：尝试在空对象引用上调用虚拟方法'void android.widget.ImageView.setImageResource(int)'

Question

我得到这个异常指出在imageLens管道的某些部分有一个空对象，但无法精确定位它。 它发出第 48 行和 setImageResource 方法的信号，但仍然无法修复它。还查看了具有类似问题的其他问题，无法将其应用于此特定代码。

这是出现错误的活动

    package com.komorebiestudio.cam_report_funcionality;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.ArrayList;
public class LensAdapter extends RecyclerView.Adapter<LensAdapter.LensViewHolder> {
    private ArrayList<LensItem> mLensList;
    public static class LensViewHolder extends RecyclerView.ViewHolder{
        public ImageView mImageLens;
        public TextView mTextViewLens;
        public TextView mTextViewBrand;
        public LensViewHolder(View itemView) {
            super(itemView);
            mImageLens = itemView.findViewById(R.id.lensimage);
            mTextViewLens = itemView.findViewById(R.id.LensTextView);
            mTextViewBrand = itemView.findViewById(R.id.LensBrandTextView);
        }
    }
    //Constructor para ingresar la informacion del recycler al arraylist
    public LensAdapter(ArrayList<LensItem> lensList){
        mLensList = lensList;
    }
    //Crea el constructor para recibir la informacion del recyclerView
    @Override
    public LensViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.lens_activity, parent, false);
        LensViewHolder lvh = new LensViewHolder(v);
        return lvh;
    }
    //recibe la informacion del recycleView y la muestra el los TextViews correspondientes
    @Override
    public void onBindViewHolder(LensViewHolder holder, int position) {
        LensItem currentItem = mLensList.get(position);
        holder.mImageLens.setImageResource(currentItem.getImageLens());
        holder.mTextViewLens.setText(currentItem.getLens());
        holder.mTextViewBrand.setText(currentItem.getBrandLens());
    }
    //Define cuantos items hay en la lista, por default es 0, pero con el cambio por .size
    //es del tamaño del Array
    @Override
    public int getItemCount() {
        return mLensList.size();
    }
}

在这里我声明了 get 方法

package com.komorebiestudio.cam_report_funcionality;
public class LensItem {
    private int mImageLens;
    private String mLens;
    private String mBrandLens;
    public LensItem( int imageLens, String lens, String brandLens){
        mImageLens = imageLens;
        mLens = lens;
        mBrandLens = brandLens;
    }
    public int getImageLens(){
        return mImageLens;
    }
    public String getLens() {
        return mLens;
    }
    public String getBrandLens() {
        return mBrandLens;
    }
}

这是将它们加在一起的活动

    package com.komorebiestudio.cam_report_funcionality;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import java.util.ArrayList;
public class LensActivity extends AppCompatActivity {
    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.lens_activity);
        ArrayList <LensItem> lensItem = new ArrayList<>();
        lensItem.add(new LensItem(R.drawable.ic_camera,"24mm","Zeiss Compact Prime"));
        lensItem.add(new LensItem(R.drawable.ic_camera2,"35mm","Angenioux"));
        lensItem.add(new LensItem(R.drawable.ic_camera3,"50mm","Cooke S5I"));
        mRecyclerView = findViewById(R.id.lens_list);
        mRecyclerView.setHasFixedSize(true);
        mLayoutManager = new LinearLayoutManager(this);
        mAdapter = new LensAdapter(lensItem);
        mRecyclerView.setLayoutManager(mLayoutManager);
        mRecyclerView.setAdapter(mAdapter);
    }
}

Answer 1

我发现了错误，我在吹扫器上调用了错误的布局。具体来说，我调用了RecyclerView布局，应该调用CardView布局。

它应该看起来像这样。

//Crea el constructor para recibir la informacion del recyclerView
@Override
public LensViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.lens_list, parent, false);
    LensViewHolder lvh = new LensViewHolder(v);
    return lvh;
}