Simplify the creation of ViewModel #android #kotlin

DemoActivity.kt

class DemoActivity : AppCompatActivity() {
    private lateinit var viewModel: MyViewModel
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        viewModel = viewModel(MyViewModel.Factory(application))
        setContentView(R.layout.activity_demo)
    }
}

ViewModelExtensions.kt

import android.arch.lifecycle.ViewModel
import android.arch.lifecycle.ViewModelProvider
import android.arch.lifecycle.ViewModelProviders
import android.support.v4.app.Fragment
import android.support.v4.app.FragmentActivity

inline fun <reified T : ViewModel> FragmentActivity.viewModel(factory: ViewModelProvider.Factory): T =
        ViewModelProviders.of(this, factory).get(T::class.java)

inline fun <reified T : ViewModel> Fragment.viewModel(factory: ViewModelProvider.Factory): T =
        ViewModelProviders.of(this, factory).get(T::class.java)

inline fun <reified T : ViewModel> FragmentActivity.viewModel(): T =
        ViewModelProviders.of(this).get(T::class.java)

inline fun <reified T : ViewModel> Fragment.viewModel(): T =
        ViewModelProviders.of(this).get(T::class.java)