Today let’s draw a dashboard meter.
I have drawn the blueprint this time:
Here is the code:
class Dashboard @JvmOverloads constructor( context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0 ) : View(context, attrs, defStyleAttr) { private val BOTTOM_ANGLE = 120 private val RADIUS = dp2px(150) private val ARM_LENGTH = dp2px(120) private val DASH_WIDTH = dp2px(2) private val DASH_LENGTH = dp2px(10) private val DASH_NUM = 12 private val paint = Paint(Paint.
Do you think Computer Science equals building websites and mobile apps?
Are you feeling that you are doing repetitive and not so intelligent work?
Are you feeling a bit sick about reading manuals and copy-pasting code and keep poking around until it works all day long?
Do you want to understand the soul of Computer Science?
If yes, read SICP!!!
I rewatched the Lecture 7A again and found that I never really understand the second half.
We often hear 3 words: app bar, action bar and tool bar. Let’s make clear of them first:
app bar: the name of the UI element/bar at the top of the app. action bar: the previous implementation of app bar, comes with some themes by default. But should not really be used anymore. tool bar: the current implementation of app bar. Should be used in replacement of action bar. Let’s create an empty project and see what it looks like by default:
Here is one clean solution of how to combine Dagger + ViewModel + SavedStateHandle.
The only difference now is that inside our ViewModel has access to SavedStateHandle. We capture this through a abstract class:
abstract class SavedStateViewModel: ViewModel() { abstract fun init(savedStateHandle: SavedStateHandle) } And the ViewModel now looks like this:
class MyViewModel @Inject constructor( private val fetchQuestionsUseCase: FetchQuestionsUseCase ) : SavedStateViewModel() { private lateinit var _questions: MutableLiveData<List<Question>> val questions: LiveData<List<Question>> get() = _questions override fun init(savedStateHandle: SavedStateHandle) { _questions = savedStateHandle.
Previously, we created a centralized ViewModelFactory which can create all ViewModels in the app:
class ViewModelFactory @Inject constructor( private val myViewModelProvider: Provider<MyViewModel>, private val myViewModel2Provider: Provider<MyViewModel2> ): ViewModelProvider.Factory { override fun <T : ViewModel?> create(modelClass: Class<T>): T { return when(modelClass) { MyViewModel::class.java -> myViewModelProvider.get() as T MyViewModel2::class.java -> myViewModel2Provider.get() as T else -> throw RuntimeException("unsupported ViewModel type: $modelClass") } } } But with more and more ViewModels being added to our app, this class will grow quickly, is there a way to mitigate this?
