Layout for Gallery Activity - Uploading an Image to Firebase

activity_gallery.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        tools:showIn="@layout/activity_gallery"
        tools:context=".GalleryActivity"
        android:padding="30dp"
        android:orientation="vertical"
>

    <ImageView
        android:id="@+id/image_preview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_image_gray_24dp"
    />

    <Button
        android:id="@+id/btn_choose_image"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Choose image"
    />

    <Button
        android:id="@+id/btn_upload_image"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Upload image"
    />

</LinearLayout>