java错误是缺少包、类、变量和方法

Question

我在Android Studio中解决文件的一些问题时遇到了困难，我有两个文件，其中我的评论指出了错误

PT-BR中有一些变量或代码片段，因为我是巴西的巴西人，来自巴西的一个堆栈溢出，但在那里，它们对我的Android Studio帮助不大

错误在于缺少包、类、变量和方法

文件ListPessoas.java（共4个错误）

package com.example.iury.livroapp;
import 安卓.support.v7.app.AppCompatActivity;
import 安卓.os.Bundle;
import 安卓.widget.Toast;
import 安卓x.recyclerview.widget.LinearLayoutManager; //error package 安卓x.recyclerview.widget does not exist
import 安卓x.recyclerview.widget.RecyclerView; //error: package 安卓x.recyclerview.widget does not exist
import java.util.List;

public class ListarPessoas extends AppCompatActivity {

    RecyclerView recyclerView; //error: cannot find symbol class RecyclerView

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_listar_pessoas);
        setTitle("Listar pessoas");

        recyclerView = findViewById(R.id.recyclerView); //error: cannot find symbol variable recyclerView
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setHasFixedSize(true);

        DatabaseHelperClass bd = new DatabaseHelperClass(this);
        List<Pessoa> pessoas = bd.getListarPessoas();

        if (pessoas.size() > 0){
            PessoaAdapter pessoaadapter = new PessoaAdapter(pessoas,ListarPessoas.this);
            recyclerView.setAdapter(pessoaadapter);
        } else {
            Toast.makeText(this, "Não existe pessoas no banco de dados.", Toast.LENGTH_SHORT).show();
        }
    }
}

文件PessoaAdapter.java（共12个错误）

package com.example.iury.livroapp;
import 安卓.app.Activity;
import 安卓.content.Context;
import 安卓.view.LayoutInflater;
import 安卓.view.View;
import 安卓.view.ViewGroup;
import 安卓.widget.Button;
import 安卓.widget.EditText;
import 安卓.widget.TextView;
import 安卓x.annotation.NonNull; //error: cannot find symbol class NonNull
import 安卓x.recyclerview.widget.LinearLayoutManager; //error: package 安卓x.recyclerview.widget does not exist
import 安卓x.recyclerview.widget.RecyclerView; //error: package 安卓x.recyclerview.widget does not exist
import java.util.List;

                                  //error: package RecyclerView does not exist
public class PessoaAdapter extends RecyclerView.Adapter<PessoaAdapter.ViewHolder> {

    List<Pessoa> pessoas;
    Context context;
    DatabaseHelperClass bd;

    public PessoaAdapter(List<Pessoa> pessoas, Context context) {
        this.pessoas = pessoas;
        this.context = context;
        bd = new DatabaseHelperClass(context);
    }
    
    @NonNull
    @Override //error: method does not override or implement a method from a supertype
    //error: cannot find symbol class NonNull
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());
        View view = layoutInflater.inflate(R.layout.activity_listar_pessoas,parent,false);
        ViewHolder viewHolder = new ViewHolder(view);
        return viewHolder;
    }
    
    @Override
    //error: cannot find symbol class NonNull
    public void onBindViewHolder(@NonNull final ViewHolder holder, final int position) {
        final Pessoa f_pessoa = pessoas.get(position);

        holder.textId_pessoa.setText(Integer.toString(f_pessoa.getId_pessoa()));
        holder.editNome_pessoa.setText(f_pessoa.getNome_pessoa());
        holder.editEmail_pessoa.setText(f_pessoa.getEmail_pessoa());
        holder.editTelefone_pessoa.setText(f_pessoa.getTelefone_pessoa());

        holder.button_update.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String nome_pessoa = holder.editNome_pessoa.getText().toString();
                String email_pessoa = holder.editEmail_pessoa.getText().toString();
                String telefone_pessoa = holder.editTelefone_pessoa.getText().toString();

                bd.UpdatePessoa(new Pessoa(f_pessoa.getId_pessoa(),nome_pessoa,email_pessoa,telefone_pessoa));
                notifyDataSetChanged(); //error: cannot find symbol method notifyDataSetChanged()
                ((Activity) context).finish();
                context.startActivity(((Activity) context).getIntent());
            }
        });

        holder.button_delete.setOnClickListener(new View.OnClickListener() {
            //error: method does not override or implement a method from a supertype
            @Override
            public void onClick(View v) {
                bd.DeletePessoa(f_pessoa.getId_pessoa());
                pessoas.remove(position);
                notifyDataSetChanged();
            }
        });

    }

    @Override //error: method does not override or implement a method from a supertype
    public int getItemCount() {
        return pessoas.size();
    }
                            //error: package RecyclerView does not exist
    public class ViewHolder extends RecyclerView.ViewHolder{
        Button button_update, button_delete;
        TextView textId_pessoa;
        EditText editNome_pessoa, editEmail_pessoa, editTelefone_pessoa;
        Button button_update_pessoa, button_delete_pessoa;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            textId_pessoa = findViewById(R.id.textId_pessoa);
            editNome_pessoa = findViewById(R.id.editNome_pessoa); //error: cannot find symbol method findViewById(int)
            editEmail_pessoa = findViewById(R.id.editEmail_pessoa);
            editTelefone_pessoa = findViewById(R.id.editTelefone_pessoa); //error: cannot find symbol method findViewById(int)
            button_delete = itemView.findViewById(R.id.button_delete_pessoa);
            button_update = itemView.findViewById(R.id.button_update_pessoa);
        }
    }
}