mercidev's questions

我正在编写一个类似于计步器的Android应用程序。我已经为每日半夜清洁脚步的功能苦苦挣扎了很长一段时间。我的功能无法正常工作，请帮助我。

听众：

    public void onSensorChanged(SensorEvent event) {
        if (event.sensor.getType() == Sensor.TYPE_STEP_COUNTER) {
            SharedPreferences prefs = getSharedPreferences("stats", Context.MODE_PRIVATE);
            float stepsAtMidnight = prefs.getFloat("steps", 0);

            float stepsToday = event.values[0] - stepsAtMidnight;

            if (stepsToday >= 0) {
                dsteps.setText(String.valueOf((int) stepsToday));
                dsteps1.setText(String.valueOf((int) stepsToday));
                float kmm = (stepsToday * 75) / 100000;
                km.setText(String.format("%.1f km", kmm));
                kcal.setText((int)(stepsToday * 0.04) + " kcal");
            }
        }
    }

警报：

public void setMidnightResetAlarm(Context context) {
        AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
        Intent intent = new Intent(context, StepCounterResetReceiver.class);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);

        Calendar calendar = Calendar.getInstance();
        calendar.setTimeZone(TimeZone.getTimeZone("Europe/Moscow"));
        calendar.set(Calendar.HOUR_OF_DAY, 0);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MILLISECOND, 0);

        Toast.makeText(context, "Alarm set for midnight", Toast.LENGTH_SHORT).show();

        alarmManager.setInexactRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(),
                AlarmManager.INTERVAL_DAY, pendingIntent);
    }

接收者：

@Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context, "Сброс шагов", Toast.LENGTH_SHORT).show();
        SharedPreferences prefs = context.getSharedPreferences("stats", Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = prefs.edit();

        float lastSavedSteps = prefs.getFloat("laststeps", 0);
        editor.putFloat("steps", lastSavedSteps);
        editor.apply();
    }

我有一个代码，允许我向 RecyclerView 添加新项目。问题是，重新启动应用程序后，该元素不会保存并且会消失。怎么解决这个问题呢？

package ru.mdev.moneybox;

import android.app.Dialog;
import android.content.SharedPreferences;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    private ImageView menu;
    private EditText search;
    private RecyclerView recview;
    private Button create;
    public ArrayList<Box> boxes;
    private BoxAdapter adapter;
    private Dialog dialog;
    private TextView check;
    private static final String BOXES_KEY = "boxes_key";
    private static final String PREFS_NAME = "ru.mdev.moneybox";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        menu = findViewById(R.id.menu);
        search = findViewById(R.id.search);
        recview = findViewById(R.id.recview);
        create = findViewById(R.id.create);
        check = findViewById(R.id.check);
        dialog = new Dialog(MainActivity.this);

        recview.setLayoutManager(new LinearLayoutManager(this));

        boxes = new ArrayList<>();
        adapter = new BoxAdapter(boxes, MainActivity.this);
        recview.setAdapter(adapter);

        create.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dialog.setContentView(R.layout.activity_create);
                dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
                dialog.setCanceledOnTouchOutside(true);
                dialog.show();

                EditText name = dialog.findViewById(R.id.name);
                EditText target = dialog.findViewById(R.id.target);
                EditText starter = dialog.findViewById(R.id.starter);
                Button ssave = dialog.findViewById(R.id.save);
                ssave.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        if (name.getText().toString().isEmpty() || target.getText().toString().isEmpty() || starter.getText().toString().isEmpty()) {
                            Toast.makeText(MainActivity.this, "Поля не могут быть пустыми", Toast.LENGTH_SHORT).show();
                        } else if (name.getText().length() > 20) {
                            Toast.makeText(MainActivity.this, "Название не может быть более 20 символов", Toast.LENGTH_SHORT).show();
                        } else {
                            boxes.add(new Box(name.getText().toString(), Integer.valueOf(target.getText().toString()), Integer.valueOf(starter.getText().toString())));
                            dialog.dismiss();
                            adapter.notifyDataSetChanged();
                        }
                    }
                });
            }
        });
    }
}