安卓基础（AndroidViewModel）

亦余心之所善兮，虽九死其犹未悔。这篇文章主要讲述安卓基础（AndroidViewModel）相关的知识，希望能为你提供帮助。
今天学习了androidViewModel，但是我根据视频上讲解，根据所讲用例，在添加依赖得时候一直报错，后来我请教大佬，他告诉我说是，因为网络得问题，国外得一些依赖有可能下不下来，所以可以下载阿里云的依赖。

implementation \'androidx.lifecycle:lifecycle-viewmodel-savedstate:1.0.0-alpha01\'

需将build.gradle(Project)更改为以下：

// Top-level build file where you can add configuration options common to all sub-projects/modules.buildscript { repositories { maven { url \'http://maven.aliyun.com/nexus/content/groups/public/\' } maven { url \'http://maven.aliyun.com/nexus/content/repositories/jcenter\' } google() //jcenter()} dependencies { classpath \'com.android.tools.build:gradle:3.5.3\'// NOTE: Do not place your application dependencies here; they belong // in the individual module build.gradle files } }allprojects { repositories { maven { url \'http://maven.aliyun.com/nexus/content/groups/public/\' } maven { url \'http://maven.aliyun.com/nexus/content/repositories/jcenter\' } google() //jcenter()} }task clean(type: Delete) { delete rootProject.buildDir }

跟着视频所作的项目是永久保存数据，在正常重启情况下，也可以保存数据。
项目还是一个简单的加减运算，两个按钮，一个Textview。
MainActivity:

package com.example.androidviewmodel; import android.arch.lifecycle.ViewModelProviders; import android.databinding.DataBindingUtil; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import androidx.lifecycle.SavedStateVMFactory; import com.example.androidviewmodel.databinding.ActivityMainBinding; public class MainActivity extends AppCompatActivity { MyViewModel myViewModel; ActivityMainBinding binding; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); binding = DataBindingUtil.setContentView(this, R.layout.activity_main); myViewModel = ViewModelProviders.of(this, new SavedStateVMFactory(this)).get(MyViewModel.class); binding.setLifecycleOwner(this); binding.setData(myViewModel); } }

MyViewModel:

package com.example.androidviewmodel; import android.app.Application; import android.arch.lifecycle.AndroidViewModel; import android.content.Context; import android.content.SharedPreferences; import android.support.annotation.NonNull; import androidx.lifecycle.LiveData; import androidx.lifecycle.SavedStateHandle; public class MyViewModel extends AndroidViewModel { SavedStateHandle handle; String key = getApplication().getResources().getString(R.string.key); String mydata = https://www.songbingjia.com/android/getApplication().getResources().getString(R.string.MY_DATA); public MyViewModel(@NonNull Application application, SavedStateHandle handle) { super(application); this.handle = handle; if (!handle.contains(key)) { load(); } }public LiveData< Integer> getnumber() { return handle.getLiveData(key); }void load() { SharedPreferences shp = getApplication().getSharedPreferences(mydata, Context.MODE_PRIVATE); int x = shp.getInt(key, 0); handle.set(key, x); }void save() { SharedPreferences shp = getApplication().getSharedPreferences(mydata, 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); } }

但是我遇到了一个问题，我跟着视频所敲的代码，就是报错，一直找不出为什么，很难受。
Build显示：