method 'java.lang.Object java.util.Map$Entry.getValue()' on a null object reference at android.arch.lifecycle.LifecycleRegistry.sync(LifecycleRegistry.java:323)
at android.arch.l
嘿,我正在试着让我的ViewModel工作,但到目前为止还没有运气。Android显示错误Cannot resolve symbol 'ViewModelProviders'。我的代码是基于的public class MainActivity extends AppCompatActivity implements
TileAdapter.TileAdap