Intent, second activity, layout

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"

    android:layout_height="match_parent"
    android:layout_margin="16dp"
    android:orientation="vertical">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="3"
        android:background="#2CEF00"
        android:gravity="center"
        android:text="Second application"
        android:textSize="34sp" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:onClick="openFirst"
        android:text="open first activity" />

</LinearLayout>