Caused by: java.lang.RuntimeException: Cannot create an instance of class com.example.lifecycleobserver.MyLocationListener
        at androidx.lifecycle.ViewModelProvider$NewInstanceFactory.create(ViewModelProvider.java:223)
        at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:278)
        at androidx.lifecycle.SavedStateViewModelFactory.create(SavedStateViewModelFactory.java:112)
        at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:185)
        at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:150)
        at com.example.lifecycleobserver.MainActivity.onCreate(MainActivity.java:18)
        at android.app.Activity.performCreate(Activity.java:7009)
        at android.app.Activity.performCreate(Activity.java:7000)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856) 
        at android.app.ActivityThread.-wrap11(Unknown Source:0) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:164) 
        at android.app.ActivityThread.main(ActivityThread.java:6494) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) 
     Caused by: java.lang.IllegalAccessException: java.lang.Class<com.example.lifecycleobserver.MyLocationListener> is not accessible from java.lang.Class<androidx.lifecycle.ViewModelProvider$NewInstanceFactory>

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راه حل‌های تو اینترنت رو پیدا کردم ولی هیچکدومش مشکل رو حل نکرد

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        MyLocationListener myLocationListener = new ViewModelProvider(this).get(MyLocationListener.class);
        Log.i(TAG, "onCreate: " + myLocationListener.getStringMutableLiveData().getValue());
        myLocationListener.getStringMutableLiveData().observe(this, new Observer<String>() {
            @Override
            public void onChanged(String s) {
                Log.i(TAG, "onChanged: " + s);
            }
        });
    }
}

class MyLocationListener extends ViewModel {
    private Timer timer = new Timer();
    private MutableLiveData<String> stringMutableLiveData = new MutableLiveData<>();
    public MyLocationListener() {
        timer.schedule(new TimerTask() {
            @Override
            public void run() {
                stringMutableLiveData.postValue("Time : " + System.currentTimeMillis());
            }
        }, 0, 1000);
    }
    public LiveData<String> getStringMutableLiveData() {
        return stringMutableLiveData;
    }
    @Override
    protected void onCleared() {
        super.onCleared();
        timer.cancel();
        timer.purge();
        timer = null;
    }
}