Develop Reference

Import dart file in flutter

I'm working on a flutter project and I want to import a dart file in my main file but I don't know how to do it.
I import my dart file first import 'package:splash/Categories.dart';
and I initialized it like that final Category _category = Category();
but I have this error Try using 'as prefix' for one of the import directives, or hiding the name from all but one of the imports
Please how can I fix it. Thank you in advance

This happens when the same class is in two different files. So if you want to use a specific class in specific file we need to use aliases.
Example:
import 'package:splash/Categories.dart';
import 'package:something/Something.dart' as name;
Use classname in Something.dart as name.class_name

Question on importing two classes with the same name - android.graphics.Color

I currently have a imported color class from another Android Library:
import com.google.ar.sceneform.rendering.Color;
but I need to import another color class:
import android.graphics.Color;
but after typing this import, it gives me the error:
so I have to end up removing the second import and use it manually like this:
mBtnColor.setColorFilter(android.graphics.Color.parseColor(color));
is there a way I can import both classes? or maybe use the second import without typing android.graphics.Color?

Create two classes: one inherits the first Color and does nothing and is called AndroidGraphicsColor and the other one inherits the appropriate class and is called AndroidSceneFormRenderingColor. Then use them.

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

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.

Android multiple packages in one project, what is R and how to import it?

I have a launcher for people with bad eyesight and a simple music player, this is my second APP so bear in mind I'm a complete noob in android and eclipse.
I tried to merge both my launcher and music player. I added the activity to the manifiest with a different intent, copied layouts and drawables to the launcher project and I added the player's package inside my /src folder.
Afterwards on the first lines of com.easyplayer.java I got this error:
import com.easyplayer.R; // the import com.easyplayer.R cannot be resolved
This is the only bug I'm getting so I suppose I did everything else fine. I imagine R must reference the player's layout, but I'm not sure how to fix it (cleaning/rebuilding doesn't work). What is the R class? And what can I do to fix this?

The R class you see is auto-generated by Android. It is a utility class that contains references to all the resources in your project. There is a few answers detailing its contents here.
You mentioned you performed a clean of your project, but you need to do a full build as well to regenerate this file.
edit: The import of the new code may have somehow invalidated your xml files. Check to see if there are any errors there, which could be preventing the R file from being re-created during a build.

if you have several packages like, com.example.app.package1 and com.example.app.package2, then import the R.java file like,
import com.example.app.R;
And if you already have import android.R; then please delete that and save the file and clean the project, problem will be solve...:)