Differences

This shows you the differences between two versions of the page.

--- android_learning:headfirst_android_development_notes:chapter_5 [2016/01/24 03:43] – mithat
+++ android_learning:headfirst_android_development_notes:chapter_5 [2016/01/24 04:45] (current) – [Additional notes] mithat
@@ Line 88: / Line 88: @@
 </WRAP>
-===== Additional notes =====
+===== p. 219 =====
+Your text suggest a ScrollView can be used as a root ViewGroup:
+<file xml content_main.xml>
+<?xml version="1.0" encoding="utf-8"?>
+<ScrollView 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"
+    android:paddingBottom="@dimen/activity_vertical_margin"
+    android:paddingLeft="@dimen/activity_horizontal_margin"
+    android:paddingRight="@dimen/activity_horizontal_margin"
+    android:paddingTop="@dimen/activity_vertical_margin"
+    tools:context="com.hfad.scrollviewdemo.MainActivity"
+    tools:showIn="@layout/activity_main">
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical">
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Top!" />
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Hello World!" />
+        ...
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Bottom!" />
+    </LinearLayout>
+</ScrollView>
+</file>
+However, in my experience this leads to unpredictable results (top of the ScrollView being obscured, etc.). A more reliable strategy seems to be nesting a ScrollView inside a root ViewGroups:
+<file xml content_main.xml>
+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout 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"
+    android:paddingBottom="@dimen/activity_vertical_margin"
+    android:paddingLeft="@dimen/activity_horizontal_margin"
+    android:paddingRight="@dimen/activity_horizontal_margin"
+    android:paddingTop="@dimen/activity_vertical_margin"
+    app:layout_behavior="@string/appbar_scrolling_view_behavior"
+    tools:context="com.hfad.scrollviewdemo.MainActivity"
+    tools:showIn="@layout/activity_main">
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Outside ScrollView"
+        android:id="@+id/textView" />
+    <ScrollView
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:id="@+id/scrollView"
+        android:layout_below="@+id/textView">
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical">
+            <TextView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="Top" />
+            <TextView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="Hello World!" />
+            ...
+            <TextView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="Bottom" />
+        </LinearLayout>
+    </ScrollView>
+</RelativeLayout>
+</file>
+Android Studio produces a warning stating that the ''android:layout_height'' attribute of the LinearLayout inside the ScrollView should be set to ''wrap_content'' rather than ''match_parent''.
+<WRAP center round info 90%>
+In the examples above, I am using string literals for the text attributes---only because this is throwaway, quick-n-dirty, prove-a-concept code.
+</WRAP>
+===== Additional notes on the UI builder =====
 If you examine the UI builder on a layout's "Design" tab, you will see that in addition to using it to add Views to your layout, you can also edit your Views' attributes.