Android Room新增数据后RecyclerView不实时刷新问题解决

问题说明 #

• 正在开发一款Android计算器应用，包含计算页、历史记录页两个页面
• 应用通过Room数据库存储三类数据：数学运算表达式、运算结果、运算时间
• 预期效果：点击「等于」按钮完成计算后，历史页可实时展示上述三类数据
• 现存异常：
  • 新增计算记录后，必须关闭重启应用才能在历史页加载到新数据，多次尝试调用notifyDataSetChanged()均未生效
  • 偶发历史页完全不显示任何数据的问题
  • 初步调整后问题仍未解决：已确认向数据库插入数据后，适配器绑定的localDataset数据集长度会增长，但RecyclerView始终无法刷新展示新数据
• 如需更多排查相关信息可随时告知

项目相关代码 #

列表适配器（CalculatorListAdapter.java） #

package com.example.simplecalculator;
import android.annotation.SuppressLint;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;


public class CalculatorListAdapter extends RecyclerView.Adapter<CalculatorListAdapter.ViewHolder> {
    public CalculatorListAdapter() {
    }

    public List<CalculationEntities> localDataset;


    public CalculatorListAdapter(List<CalculationEntities> dataset) {
        localDataset = dataset;

    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.calculation_history_item, parent, false);
        return new ViewHolder(view);
    }


    @Override
    public void onBindViewHolder(@NonNull CalculatorListAdapter.ViewHolder holder, int position) {
        holder.itemView.setTag(position);

        holder.tvCalculation.setText(localDataset.get(position).calculation);
        holder.tvResult.setText(localDataset.get(position).result);
        holder.tvTimeStamp.setText(localDataset.get(position).timeStamp);
    }


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

    public static class ViewHolder extends RecyclerView.ViewHolder {
        public final TextView tvResult;
        public final TextView tvCalculation;
        public final TextView tvTimeStamp;


        public ViewHolder(View itemView) {
            super(itemView);

            tvCalculation = (TextView) itemView.findViewById(R.id.tvOperation);
            tvResult = (TextView) itemView.findViewById(R.id.tvResult);
            tvTimeStamp = (TextView) itemView.findViewById(R.id.tvTimeStamp);
        }
    }
}

历史记录页Fragment（History.java） #

package com.example.simplecalculator;

import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.room.RoomDatabase;

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

import java.util.Arrays;
import java.util.List;


public class History extends Fragment {


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // 加载页面布局
        return inflater.inflate(R.layout.fragment_history, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        RecyclerView rvHistory = view.findViewById(R.id.rvCalculationHistory);
        List<CalculationEntities> dataset = Arrays.asList(Calculator.database.CalculatorDao().getAllCalculations());

        CalculatorListAdapter calculatorListAdapter = new CalculatorListAdapter(dataset);
        rvHistory.setAdapter(calculatorListAdapter);
        rvHistory.setLayoutManager(new LinearLayoutManager(getContext()));

        super.onViewCreated(view, savedInstanceState);
    }
}

DAO接口（CalculatorDao.java） #

package com.example.simplecalculator;

import androidx.room.Dao;
import androidx.room.Insert;
import androidx.room.OnConflictStrategy;
import androidx.room.Query;

@Dao
public interface CalculatorDao {

    @Query("SELECT * FROM CalculationEntities WHERE calculation LIKE :name LIMIT 1")
    CalculationEntities findByName(String name);

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    void insertAll(CalculationEntities... calculations);

    @Query("SELECT * FROM CalculationEntities")
    CalculationEntities[] getAllCalculations();

    @Query("DELETE FROM CalculationEntities")
    void deleteAll();
}

数据实体类（CalculationEntities.java） #

package com.example.simplecalculator;

import androidx.room.ColumnInfo;
import androidx.room.Entity;
import androidx.room.PrimaryKey;

@Entity
public class CalculationEntities {

    @PrimaryKey(autoGenerate = true)
    public int CalculationID;

    @ColumnInfo(name="calculation")
    public String calculation;

    @ColumnInfo(name="result")
    public String result;

    @ColumnInfo(name="timeStamp")
    public String timeStamp;
}

数据库定义类（CalculatorDatabase.java） #

package com.example.simplecalculator;

import androidx.room.Database;
import androidx.room.RoomDatabase;

@Database(entities = {CalculationEntities.class}, version = 1)
public abstract class CalculatorDatabase extends RoomDatabase {
    public abstract CalculatorDao CalculatorDao();
}

内容的提问来源于stack exchange，提问作者Zibal