java - 错误: cannot find symbol variable itemsAdapter

Question

我正在遵循教程，但无法成功运行我的项目。我不断收到错误:找不到符号变量 itemsAdapter，即使我的类位于同一文件夹中。有任何想法吗？谢谢 MainActivity.java itemsAdapter.javaMainActivity.java:

package com.example.simpletodo;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.widget.Button;
import android.widget.EditText;


import java.util.ArrayList;
import java.util.List;



public class MainActivity extends AppCompatActivity {

    List<String> items;

    Button btnAdd;
    EditText etItem;
    RecyclerView rvItems;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnAdd = findViewById(R.id.btnAdd);
        etItem = findViewById(R.id.etItem);
        rvItems = findViewById(R.id.rvItems);

        items = new ArrayList<>();
        items.add("Buy milk");
        items.add("Go to the gym");
        items.add("Email Autumn");

        itemsAdapter ItemsAdapter;
        ItemsAdapter = new itemsAdapter(items);
        rvItems.setAdapter(itemsAdapter);
        rvItems.setLayoutManager(new LinearLayoutManager(this));

    }
}

ItemsAdapter.java: 包 com.example.simpletodo;

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

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

public class itemsAdapter extends 
   RecyclerView.Adapter<itemsAdapter.ViewHolder>{

      List<String> items;

    public itemsAdapter(List<String> items) {
          this.items = items;

    }

    // @NonNull
    @Override
   // creates each view
   public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
      // Use layout inflator to inflate a view
      View todoView = LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_1, parent, false);
      // wrap it inside a View Holder and return it
      return new ViewHolder(todoView);
  }  

   // responsible for binding data to a particular view holder
   @Override
   public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        // Grab the item at the position
       String item = items.get(position);
      // Bind the item into specified view holder
      holder.bind(item);

    }

    // the # of items available in the data
   @Override
  public int getItemCount() {
        return 0;
   }

       // Container to provide easy access to views that represent each row of the list
     class ViewHolder extends RecyclerView.ViewHolder {

    public ViewHolder(@NonNull View itemView) {
        super(itemView);
    }

    // Update the view inside of the view holder with this data
    public void bind(String item) {
    }
}

Answer 1

在MainActivity.java的第41行中，itemsAdapter需要是ItemsAdapter

PS:您的 itemsAdapter 命名标准与惯例相反。该类应命名为 ItemsAdapter，变量/实例应为 itemsAdapter