Udacity | Data Analyst Nano-degree Projects | Machine Learning library

Your code is fine, except that it assumes the list is not empty. You should protect your code against that situation. For the rest it can be simplified to this:

I guess I also did this project for my NanoDegree and I am impressed by your code.

Inside my ViewModel I created 3 variables for each EditText

• MutableLiveData - to update the value inside the viewModel

• LiveData to expose value outside viewModel e.g. in a fragment (you won't really need this)

• Public Variable to monitor value of MutableLiveData and expose this to your xml thus achieving the 2-Way Binding.

Then I and would create a Shared ViewModel to share data between ShoeDetailsFragment and ShoeListingFragment .

Inside the SharedViewModel

I created 3 variables for each EditText (this is just the first 2 Edittexts)

As @javdromero said in the comment, wordView is just a reference for the TextView View Object. We are just creating a TextView object. Setting the text on it and adding it to the rootView. rootView is just a reference name for the LinearLayout in your example. None if the reference names will set the id for the View Objects. The scope of wordView is limited to every loop while doing the for loop iteration, once the index increments you are having another View Object reference being assigned to wordView.

Gradle is an app that Android Studio uses to manage loading the libraries of code the project is built with (among other things). But since this project you downloaded is about 5 years old, the version of Gradle in the project may not match up with what Android Studio's Android plugin can support.

Typically, the Gradle app is actually part of the project. You'll see it in the gradle/wrapper directory in the project. You can update the version by editing the file gradle-wrapper.properties, by changing the value in the distributionUrl line. I think you need to make the version at least 6.7.1 if you have a recently updated version of Android Studio, so change that line to look like this:

This class

If you literally quoted Udacity, their explanations are wrong. random1’s value is not assigned at compile time because random() is called at runtime when the class is first used. Only then is its value assigned. Afterwards, in the same application session, the value will remain constant. But the same compiled app will have different values for it on separate sessions of the application.

And random2’s lambda is not executed every time the variable is referenced. It is executed only when it is invoked with a call to invoke() (or operator equivalent). The lambda object itself will always be the same instance.

So, your own test confirms how they described both cases incorrectly.

This is probably a matter of opinion. Mine is that the callback should be an object, or anonymous object, but not a companion object.

All it's doing is comparing properties of two objects. It doesn't have to hold any state. So it makes sense for it to be a singleton object rather than a class that you have to instantiate. Whether you define it as a named singleton object or define in place as an anonymous object assigned to a property doesn't make much different in communicating intent.

But it doesn't make sense to me to make it a companion. It's already nested and has a name. All companion does is suggest that you should need to call its functions directly and that the name PhotoGridAdapter should also be thought of as a callback. For instance, it enables you to pass the name PhotoGridAdapter to some other adapter as its DiffUtil callback, which is nonsensical. The only reason it might possibly make sense is if you also want to use it as a utility for comparing items, so you could call functions like PhotoGridAdapter.areContentsTheSame directly. However, I don't think this is likely. Usually, the contents of the callback's functions are either very trivial like passing through equals() or they are very specific to the nature of updating the displayed list.

try change WordAdapter.java (Class) audio = MediaPlayer.create(getContext(), currentWord.getAudioResourceId()); to audio = MediaPlayer.create(getContext().getApplicationContext(), currentWord.getAudioResourceId());

Inside MainActivity

remove setContentView(R.layout.activity_main)

and add

val binding: ActivityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)

Use binding for all the UI stuff.