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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
Posted by Jonathan Grieve
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
Ben Deitch
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
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