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Android Build a Simple Android App with Kotlin Improving Our Code Dynamically Changing the Background Color

Jonathan Grieve
MOD
Jonathan Grieve
Treehouse Moderator 91,253 Points

Changing background colour of a layout dynamically

I'm a bit confused here.

How am I supposed to change the colour of the required layout without an Event Listener. But then, I attach that to a Button, don't I? I don't see one, so do I create one? or is there a bug to the challenge! :)

Thanks.

MealActivity.kt
import android.app.Activity
import android.os.Bundle
import android.widget.TextView
import android.widget.RelativeLayout

class MealActivity : Activity() {

  override fun onCreate(savedInstanceState: Bundle) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_meal)

    val foodLabel = findViewById(R.id.foodTextView) as TextView
    val drinkLabel = findViewById(R.id.drinkTextView) as TextView
    val mealLayout = findViewById(R.id.mealLayout) as RelativeLayout


    mealLayout.setBackgroundColor(Color.GREEN);
  }
}

1 Answer

Ben Deitch
STAFF
Ben Deitch
Treehouse Teacher

Hey Jonathan!

While that does work, with Kotlin we don't need to use the 'setXXXXX' methods; we can just set the properties directly: mealLayout.backgroundColor = Color.GREEN

Also, get rid of that semicolon :)

Jonathan Grieve
Jonathan Grieve
Treehouse Moderator 91,253 Points

Thanks Ben, I think I understand now :)

The semi colons are a habit from Java I'm trying very hard to kick lol