要实现关机后数据也不会丢失，需要使用到 AndroidViewModel,SaveStateHandle 和 SharePreferences 要达到的目的就是将数据保存成这个亚子

就不会出现app在异常闪退或者关机后数据的丢失了注意在使用SaveStateHandle和binding的时候需要在gradle里面设置一波

数据类

package com.example.applicationtest04;import android.app.Application;import android.content.Context;import android.content.SharedPreferences;import androidx.annotation.NonNull;import androidx.lifecycle.AndroidViewModel;import androidx.lifecycle.LiveData;import androidx.lifecycle.MutableLiveData;import androidx.lifecycle.SavedStateHandle;public class MyVIewModel extends AndroidViewModel { SavedStateHandle handle; //声明savedstatehandle 类型 String shpName = getApplication().getResources().getString(R.string.shp_name); String key = getApplication().getResources().getString(R.string.key); public MyVIewModel(@NonNull Application application, SavedStateHandle handle) {  super(application);  this.handle = handle;  if(!handle.contains(key)){   load();  } } public LiveData getNumber(){  return handle.getLiveData(key); } public void load(){  SharedPreferences shp = getApplication().getSharedPreferences(shpName, Context.MODE_PRIVATE);  int x = shp.getInt(key,0);  handle.set(key,x); } public void save(){  SharedPreferences shp = getApplication().getSharedPreferences(shpName,Context.MODE_PRIVATE);  SharedPreferences.Editor editor = shp.edit();  editor.putInt(key,getNumber().getValue());  editor.apply(); } public void add(int x){  handle.set(key,getNumber().getValue()+x); }}//这段代码里面有几个重要的点就是在使用handle的时候要注意使用的数据是liveData

Mainactive类

package com.example.applicationtest04;import androidx.appcompat.app.AppCompatActivity;import androidx.databinding.DataBindingUtil;import androidx.lifecycle.SavedStateVMFactory;import androidx.lifecycle.ViewModelProvider;import androidx.lifecycle.ViewModelProviders;import android.os.Bundle;import com.example.applicationtest04.databinding.ActivityMainBinding;public class MainActivity extends AppCompatActivity { MyVIewModel myVIewModel; ActivityMainBinding binding; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  binding = DataBindingUtil.setContentView(this,R.layout.activity_main);  this.myVIewModel = ViewModelProviders.of(this,new SavedStateVMFactory(this)).get(MyVIewModel.class);  binding.setData(myVIewModel);  binding.setLifecycleOwner(this); } @Override protected void onPause() {  super.onPause();  myVIewModel.save(); }}//这段代码的重点就是使用onPause这个声明周期的函数来调用save()函数

布局xml