Androidのメーカーリサイクラー表示削除項目

その他 2022-05-19 00:05:12 訪問数: 0
イーサン・ビアズリー：

私は自分のリサイクルビューから項目を削除しようとしています。私はリサイクルの項目をクリックするたびに、それは、このエラーを私に提供して表示します。

、java.lang.NullPointerExceptionが：NULLオブジェクト参照に「ボイドuk.edu.le.co2103.myrecipebook.RecipeListAdapter.removeItem（INT、java.util.Listに）」仮想メソッドを起動しようとし

私は私のリストはinitalized位置やリストの両方がそれらの値を持っていることを確認するためにログを使用されていることを確認してきました。

リスト：[uk.edu.le.co2103.myrecipebook.Recipe@f4d5298、uk.edu.le.co2103.myrecipebook.Recipe@ca6aaf1] D / MAIN活動：インデックス：0

ここに私の主な活動のコードです

public class MainActivity extends AppCompatActivity implements 
RecipeListAdapter.OnItemClickListener  {
private static final String TAG = "MAIN ACTIVITY";
private static final int RESULT_UPDATED = 300;
private RecipeViewModel mRecipeViewModel;
    public static final int NEW_WORD_ACTIVITY_REQUEST_CODE = 1;
    public String Name;
    public String Ingredients;
    public String Method;
    private RecipeListAdapter mAdapter;
    private RecipeDao recDao;
    Menu menu;
List<Recipe> recipesList = new ArrayList<>();

ListView search_items;

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);
        RecyclerView recyclerView = findViewById(R.id.recyclerview);
        RecipeListAdapter mAdapter = new RecipeListAdapter(this);
        recyclerView.setAdapter(mAdapter);
        mAdapter.setOnItemClickListener(MainActivity.this);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        mRecipeViewModel = new ViewModelProvider(this).get(RecipeViewModel.class);

        Log.d(TAG, "SIZE OF LIST: "+ recipesList);
        mRecipeViewModel.getAllRecipes().observe(this, new Observer<List<Recipe>>() {
            @Override
            public void onChanged(@Nullable final List<Recipe> recipes) {
                // Update the cached copy of the words in the adapter.
                int size = mAdapter.getItemCount();
                Log.d(TAG, "List of List : " + recipes);
                recipesList= recipes;
                mAdapter.setWords(recipes);
            }
        });

        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, AddRecipeActivity.class);
                startActivityForResult(intent, NEW_WORD_ACTIVITY_REQUEST_CODE);
            }
        });



}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == NEW_WORD_ACTIVITY_REQUEST_CODE && resultCode == RESULT_OK) {
        ArrayList<String> rData = data.getStringArrayListExtra(AddRecipeActivity.EXTRA_REPLY);
        String name = rData.get(0);
        String ingredients = rData.get(1);
        String method = rData.get(2);
        Recipe recipe = new Recipe(name, ingredients, method);
        RecipeViewModel.insert(recipe);
    }
   else {
        Toast.makeText(
                getApplicationContext(),
                R.string.empty_not_saved,
                Toast.LENGTH_LONG).show();
    }
}

@Override
public void onItemClick(int position, View view) {
        Log.d(TAG, "onItemClick Position: " + position);
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(this);
    alertDialog.setTitle("Edit or Delete...");
    alertDialog.setPositiveButton("Edit", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {
            recipesList.get(position); //clicked item
            Intent update = new Intent(MainActivity.this, UpdateRecipeActivity.class);
            update.putExtra("Name", recipesList.get(position).getName()); //
            update.putExtra("Ingredients", recipesList.get(position).getIngredients());
            update.putExtra("Method", recipesList.get(position).getMethod());
            startActivity(update);

        }

    });
    alertDialog.setNegativeButton("Delete", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {
            //Delete

            Log.d(TAG, "List: " + recipesList);
            Log.d(TAG, "Index: " + position);
            int removeIndex = position;
            recipesList.remove(removeIndex);


        }
    });
    alertDialog.setNeutralButton("Cancel", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {

        }
    });
    alertDialog.show();
}

ここに私のアダプタのコードがあります

 public class RecipeListAdapter extends 
RecyclerView.Adapter<RecipeListAdapter.RecipeViewHolder> {
private static final String TAG = "ADAPTER";
private OnItemClickListener mListener;


public interface OnItemClickListener{
    void onItemClick(int position, View view);
}
public void setOnItemClickListener(OnItemClickListener listener){
    mListener = listener;
}

class RecipeViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
    private final TextView recipeItemView;

    private RecipeViewHolder(View itemView) {
        super(itemView);
        recipeItemView = itemView.findViewById(R.id.textView);
        itemView.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                if (mListener != null){
                    int position = getAdapterPosition();
                    if (position != RecyclerView.NO_POSITION){
                        mListener.onItemClick(position, v);
                    }
                }
            }
        });
    }

    @Override
    public void onClick(View view) {
        mListener.onItemClick(getAdapterPosition(), view);
    }
}

private final LayoutInflater mInflater;
private List<Recipe> mRecipes; // Cached copy of words

RecipeListAdapter(Context context) {
    mInflater = LayoutInflater.from(context);
}

@Override
public RecipeViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View itemView = mInflater.inflate(R.layout.recyclerview_item, parent, false);
    return new RecipeViewHolder(itemView);
}

@Override
public void onBindViewHolder(RecipeViewHolder holder, int position) {
    if (mRecipes != null) {
        Recipe current = mRecipes.get(position);
        holder.recipeItemView.setText(current.getName());
    } else {
        // Covers the case of data not being ready yet.
        holder.recipeItemView.setText("No Recipes");
    }
}

void setWords(List<Recipe> recipes){
    mRecipes = recipes;
    notifyDataSetChanged();
}

public void deleteItem(final int position) {
    mRecipes.remove(position);
    notifyItemRemoved(position);
}


@Override
public int getItemCount() {
    if (mRecipes != null)
        return mRecipes.size();
    else return 0;
}
public interface OnNoteListener{}

}

ここでは完全なエラーが出力され

2020-04-02 15:27:30.553 5522-5522/uk.edu.le.co2103.myrecipebook E/AndroidRuntime: FATAL EXCEPTION: main
Process: uk.edu.le.co2103.myrecipebook, PID: 5522
java.lang.NullPointerException: Attempt to invoke virtual method 'void uk.edu.le.co2103.myrecipebook.RecipeListAdapter.deleteItem(int)' on a null object reference
    at uk.edu.le.co2103.myrecipebook.MainActivity$4.onClick(MainActivity.java:133)
    at androidx.appcompat.app.AlertController$ButtonHandler.handleMessage(AlertController.java:167)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:216)
    at android.app.ActivityThread.main(ActivityThread.java:7464)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:549)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:955)
11月Özdemir：

私はあなたのアダプターを変更しました。私はいくつかの問題が見つかりました：

public class RecipeListAdapter extends 
RecyclerView.Adapter<RecipeListAdapter.RecipeViewHolder> {
private static final String TAG = "ADAPTER";
private OnItemClickListener mListener;


public interface OnItemClickListener{
  void onItemClick(int position, View view);
}
public void setOnItemClickListener(OnItemClickListener listener){
  mListener = listener;
}

class RecipeViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
private final TextView recipeItemView;

private RecipeViewHolder(View itemView) {
    super(itemView);
    recipeItemView = itemView.findViewById(R.id.textView);
    itemView.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v){
            if (mListener != null){
                int position = getAdapterPosition();
                if (position != RecyclerView.NO_POSITION){
                    mListener.onItemClick(position, v);
                }
            }
        }
    });
}

@Override
public void onClick(View view) {
    mListener.onItemClick(getAdapterPosition(), view);
}
}

private final LayoutInflater mInflater;
private List<Recipe> mRecipes; // Cached copy of words

RecipeListAdapter(Context context) {
  mInflater = LayoutInflater.from(context);
}

@Override
public RecipeViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
  View itemView = mInflater.inflate(R.layout.recyclerview_item, parent, false);
  return new RecipeViewHolder(itemView);
}

@Override
public void onBindViewHolder(RecipeViewHolder holder, int position) {
  if (mRecipes != null) {
     Recipe current = mRecipes.get(position);
     holder.recipeItemView.setText(current.getName());
} else {
    // Covers the case of data not being ready yet.
     holder.recipeItemView.setText("No Recipes");
  }
}

void setWords(List<Recipe> recipes){
  mRecipes = recipes;
  notifyDataSetChanged();
}

public void deleteItem(final int position) {
  mRecipes.remove(position);
  notifyItemRemoved(position);
}


@Override
public int getItemCount() {
  if (mRecipes != null)
    return mRecipes.size();
  else return 0;
}
public interface OnNoteListener{}
}

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