Nested LinearLayout does not align to parent ScrollView? - android-layout

Question

I have a fragment with two horizontal Buttons (yellow = fragment_test_button_container) at the bottom of my fragment. I would like to use the remaining area (red = fragment_test_scrollview) for a ScrollView It is reuiqred that my ScrollView consist of one layout (turquoise = fragment_test_check) only . This can then in turn have further layouts, as you can see in the attached fragment_test.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.TestFragment">
<ScrollView
android:id="#+id/fragment_test_scrollview"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#id/fragment_test_button_container"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHeight_percent=".84"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<LinearLayout
android:id="#+id/fragment_test_check"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<LinearLayout
android:id="#+id/fragment_test_front_photo_container"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight=".28"
android:orientation="horizontal">
<TextView
android:id="#+id/fragment_test_front_photo_title"
style="#style/myapp_MediumTextStyle"
android:layout_width="#dimen/myapp_test_fragment_textview_width"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginStart="24dp"
android:text="#string/fragment_test_front_photo_title_text" />
<ImageView
android:id="#+id/fragment_test_front_photo"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
<LinearLayout
android:id="#+id/fragment_test_back_photo_container"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight=".28"
android:orientation="horizontal">
<TextView
android:id="#+id/fragment_test_back_photo_title"
style="#style/myapp_MediumTextStyle"
android:layout_width="#dimen/myapp_test_fragment_textview_width"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginStart="24dp"
android:text="#string/fragment_test_back_photo_title_text" />
<ImageView
android:id="#+id/fragment_test_back_photo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical" />
</LinearLayout>
<!-- ADDITIONAL DATA -->
<LinearLayout
android:id="#+id/fragment_test_data_container"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight=".34"
android:orientation="vertical"
android:paddingStart="24dp"
android:paddingEnd="24dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="#+id/fragment_test_value1_label"
style="#style/myapp_MediumTextStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:text=„Value1^“ />
<TextView
android:id="#+id/fragment_test_value1_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginStart="24dp" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="#+id/fragment_test_value2_label"
style="#style/myapp_MediumTextStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:text=„Value2“ />
<TextView
android:id="#+id/fragment_test_value2_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginStart="24dp" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="#+id/fragment_test_value3_label"
style="#style/myapp_MediumTextStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:text="Ausstellungsdatum" />
<TextView
android:id="#+id/fragment_test_value3_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginStart="24dp" />
</LinearLayout>
</LinearLayout>
</LinearLayout>
</ScrollView>
<LinearLayout
android:id="#+id/fragment_test_button_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:paddingStart="24dp"
android:paddingEnd="24dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/fragment_test_scrollview">
<Button
android:id="#+id/fragment_test_back_button"
style="#style/myapp_ContinueBackButtonStyle"
android:layout_width="0dp"
android:layout_height="#dimen/myapp_continueBackButton_height"
android:layout_weight="1"
android:background="#color/myapp_colorPrimary"
android:text=„back“
android:textColor="#FFFFFF" />
<Button
android:id="#+id/fragment_test_next_button"
style="#style/myapp_ContinueBackButtonStyle"
android:layout_width="0dp"
android:layout_height="#dimen/myapp_continueBackButton_height"
android:layout_marginStart="24dpVerySmall"
android:layout_weight="1"
android:background="#color/myapp_colorPrimary"
android:text="continue"
android:textColor="#FFFFFF" />
</LinearLayout>
</android.support.constraint.ConstraintLayout>
But my turqoise (fragment_test_check) area is not aligned fully with the blue area (fragment_test_scrollview), altough I wrote match_parent. I would like the heigth of turqoise area as the blue area.
Why is my turqoise area dangling in half the blue area?

Answer 1

Set android:fillViewport="true" in your ScrollView.
fillViewport stretches the content's height to the viewport's boundaries, when set true. In simple words, fillViewport decides whether the nested contents of the layout should match the parent's boundaries or not. Thus, to make the nested layout match the parent's boundary, set fillViewport to true
Moreover, the layout_gravity for nested components should be 1 or whatsoever you define in weight_sum of parent layout, whereas in your case it is 0.90 .