Calculate the time it takes to achieve your money goal in Kotlin
Hi yes I would store the textEdit references in a field of the class (not actual global scope), if you want to access them more often. 

Running through the view hierarchy to find it on each click is not the most performant thing for more complex layout and so not best practice. These references stay valid until onDestroyed is called, so it's ok to store them.

BUT with Kotlin you would usually do it like this without casts etc. https://kotlinlang.org/docs/tutorials/android-plugin.html

import kotlinx.android.synthetic.main.activity_main.*

class MyActivity : Activity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        resultsButton.setOnClickListener {
            // Either try catch NumberFormatException or validating the string with
            // TextWatcher will be required to avoid problems here, but also in the original code.
            calculateAndDisplayTimeUntilMoneyGoal(
                goal: Float.valueOf(moneyField.getText().toString()),
                salary: Float.valueOf(salaryField.getText().toString()), 
                increaseInPercent: Float.valueOf(increaseField.getText().toString()))
        }
    }
};