Develop Reference

MainActivity not reading Subfolders Android Java

I created an application that uses the Room, ViewModel approach. I created subfolders to organize my code as shown in the photo:
How do I make my Main Activity recognize the code created in the subfolders? I tried invalidate caches/restart already and tried many times to rebuild the project.

There was an issue when I created my folders. I used New->Folder->Java Folder when the right process should be New->Package

You have to write an import statement for the classes to be recognized:
import com.example.laundry.data.ViewModel.CustomerViewModel

I think there are various ways to solve this problem.
Process 1.
For your Adapter import this
import com.example.laundry.adapter.CustomerListAdapter;
For your ViewModel import this
import com.example.laundry.data.ViewModel.CustomerViewModel;
Process 2
If you write down your adapter/model class name it will show some popup. From there you can select.
just like when I tried to import InfiniteScrollAdapter I got these options
Process 3
Please check if you have already import that adapter/model class with the different package names. Just delete that line and import again with alt+ enter

custom imports?

I see people are doing like this:
import com.inducesmile.androidlocationtracking.database.DatabaseQuery;
and regards that import, this variable
private DatabaseQuery mQuery;
turns red.
it's different from something familiar like this:
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
can someone explain what it is:
com.inducesmile.androidlocationtracking.database.DatabaseQuery
and how do we fix it,
or how do we change it to our own website?
basically, I don't understand how to fix that error. thank you very much.

So, it turns out. it has a class name DatabaseQuery
and the com.inducesmile.androidlocationtracking.database is the package hierarcy, so, just follow the rule, you're good to go

Android, Type argument listadapter

so i'm following a guide online to make a room db. In the adapter section i followed his way of doing it but when i did it, i keep having the "No Type Argument expected for Interface ListAdapter".
Error example: https://imgur.com/kPT7DkE
Here's the whole project so far on github.
https://github.com/OlivierLabelle/BudgetProject/tree/master/app/src/main/java/com/example/android/budgetproject
And the guide i was following.
https://medium.com/#trionkidnapper/recyclerview-more-animations-with-less-code-using-support-library-listadapter-62e65126acdb

So with the help of devboi, i found out i was using the wrong import.
In the top right corner on the Dev documentation it show the right import.
https://imgur.com/vGrCOVd
And here how the import on my project should look like.
import android.support.v7.recyclerview.extensions.ListAdapter

Just came across this very problem myself.
If you're using AndroidX/Jetpack/whatever the official name is I'm still new at this, Android Studio might
import android.widget.ListAdapter
automatically, but the one you want is
import androidx.recyclerview.widget.ListAdapter

From what I see in your code, you should replace ListAdapter<Transaction> with ListAdapter<Transaction, Viewholder>.
You can see an example in the docs here :(https://developer.android.com/reference/android/support/v7/recyclerview/extensions/ListAdapter.html), where ListAdapter has 2 arguments inside the diamonds: one for the list-object and the other for your custom viewholder.
Hope this helps.

Required:android.app.Fragment error

I am working on a simple application of tabs but when I do the return I throw this error I do not really know how to solve it, I read something about importing and you put "import android.app.Fragment;" But I already have it that way. I would appreciate if I can resolve my doubt to the point of this error thanks

As I cannot comment yet I will give a full answer altho you haven't provided full details I can guess your problem.
Answer:
You probably have different imports on your Fragment class and on your Activity as from your pic on your activity you import this:
import android.app.Fragment;
and on your fragment you probably import this:
import android.support.v4.app.Fragment;
meaning its not the same class therefore your ide yells that you have a class mismatch
you should import only one of these on both your activity and fragment..
gl!

What is an alternative for using com.nineoldandroids library

I want to replace the dependency of com.nineoldandroids library from my project and replace it with an android native library.
I am trying to make a project based on this http://www.tutecentral.com/android-swipe-listview/ .
However, I don't need to have support for android versions less than v11. Therefore there is no need to use this library. But I cannot find what to use in its place, while not making changes to the code itself.
The project import the classes
import com.nineoldandroids.animation.Animator;
import com.nineoldandroids.animation.AnimatorListenerAdapter;
import com.nineoldandroids.animation.ValueAnimator;
import com.nineoldandroids.view.ViewHelper;
import static com.nineoldandroids.view.ViewHelper.setAlpha;
import static com.nineoldandroids.view.ViewHelper.setTranslationX;
import static com.nineoldandroids.view.ViewPropertyAnimator.animate;
Thank you.

I had the same issue, wanted to get rid of nineoldandroids library.
As per #Selvin comment this is what you need to do:
1.) Remove all Imports
2.) Animation and ValueAnimator are available as part of the android.animation package
3.) ViewHelper doesn't really do anything that is not already available as part of each view's method.
For example:
ViewHelper.setScaleX -> view.setScaleX
ViewHelper.setY -> view.setY
ViewHelper.setAlpha -> view.setAlpha
Hope it helps.