Android: I am trying to access the button using id name in main activity but its showing an error-CodePudding

<Button
    android:id="@ id/createBirthdayButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="200dp"
    android:padding="20dp"
    android:text="@string/press_to_create"
    android:textAllCaps="false"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.498"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@ id/Sample_message_1" />

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        createBirthdayButton      // This is  not working
    }

Here id name is "createBirthdayButton" but i am not able to access it in my Main Activity class

CodePudding user response：

Please use like this :

class MainActivity : AppCompatActivity() { 

 lateinit var button : Button

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

    button = findViewById(R.id.yourButtonId)

    }
}

CodePudding user response：

unless you are using view binding (i can't see that in your code and also you are using setContentView(R.layout.activity_main) ), you need to cast your view first like the top comments:

Button createBirthdayButton =findViewById(R.id.createBirthdayButton)

and if in the future you decided to go with view binding, it will be like this:

binding.createBirthdayButton