ScrollView in Android

In Android, a ScrollView is a view group that is used to make vertically scrollable views. A scroll view contains a single direct child only. In order to place multiple views in the scroll view, one needs to make a view group(like LinearLayout) as a direct child and then we can define many views inside it. A ScrollView supports Vertical scrolling only, so in order to create a horizontally scrollable view, HorizontalScrollView is used.

XML attributes of ScrollView

Attribute

Description

android:fillViewport Defines whether the scrollview should stretch its content to fill the viewport.

Inherited Attributes:

From FrameLayout



Attributes

Description

android:measureAllChildren Determines whether to measure all children or just those in the VISIBLE or INVISIBLE state when measuring. Defaults to false.

From View

Attributes

Description

android:alpha alpha property of the view, as a value between 0 (completely transparent) and 1 (completely opaque).
android:background A drawable to use as the background. 
android:clickable Defines whether this view reacts to click events.
android:contentDescription Defines text that briefly describes content of the view.
android:id Supply an identifier name for this view, to later retrieve it with View.findViewById() or Activity.findViewById().
android:isScrollContainer Set this if the view will serve as a scrolling container, meaning that it can be resized to shrink its overall window so that there will be space for an input method.
android:minHeight Defines the minimum height of the view.
android:minWidth Defines the minimum width of the view.
android:onClick Name of the method in this View’s context to invoke when the view is clicked.
android:padding Sets the padding, in pixels, of all four edges.
android:scrollbars Defines which scrollbars should be displayed on scrolling or not.

From ViewGroup

Attributes

Description



android:addStatesFromChildren Sets whether this ViewGroup’s drawable states also include its children’s drawable states.
android:animateLayoutChanges Defines whether changes in layout should cause a LayoutTransition to run.
android:clipChildren Defines whether a child is limited to draw inside of its bounds or not.
android:clipToPadding Defines whether the ViewGroup will clip its children and resize any EdgeEffect to its padding, if padding is not zero.
android:layoutAnimation Defines the layout animation to use the first time the ViewGroup is laid out.
android:layoutMode Defines the layout mode of this ViewGroup.
android:splitMotionEvents Sets whether this ViewGroup should split MotionEvents to separate child views during touch event dispatch.

Approach

This example demonstrates the steps involved to create a ScrollView in Android using Kotlin.

Step 1: Create a new project

  1. Click on File, then New => New Project.
  2. Choose “Empty Activity” for the project template.
  3. Select language as Kotlin.
  4. Select the minimum SDK as per your need.

Step 2: Modify strings.xml 

Add some strings inside the strings.xml file to display those strings in the app.

strings.xml

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<resources>
    <string name="app_name">gfgapp_scrollview</string>
    <string name="scrolltext">Kotlin is a statically typed,
                 general-purpose programming language developed
                 by JetBrains, that has built world-class IDEs 
                 like IntelliJ IDEA, PhpStorm, Appcode, etc.
                 It was first introduced by JetBrains in 2011 
                 and a new language for the JVM. Kotlin is 
                 object-oriented language, and a “better language” 
                 than Java, but still be fully interoperable
                 with Java code. Kotlin is sponsored by Google, 
                 announced as one of the official languages for 
                 Android Development in 2017. 
                 Advantages of Kotlin language:
                 Easy to learn – Basic is almost similar to java.
                 If anybody worked in java then easily understand
                 in no time. Kotlin is multi-platform – Kotlin is
                 supported by all IDEs of java so you can write 
                 your program and execute them on any machine
                 which supports JVM. It’s much safer than Java.
                 It allows using the Java frameworks and libraries 
                 in your new Kotlin projects by using advanced 
                 frameworks without any need to change the whole
                 project in Java. Kotlin programming language, 
                 including the compiler, libraries and all the
                 tooling is completely free and open source and
                 available on github. Here is the link for 
                 Github https://github.com/JetBrains/kotlin 
                 Applications of Kotlin language:
                 You can use Kotlin to build Android Application. 
                 Kotlin can also compile to JavaScript, and making
                 it available for the frontend. It is also designed 
                 to work well for web development and server-side 
                 development.Kotlin is a statically typed, general-purpose
                 programming language developed by JetBrains that 
                 has built world-class IDEs like IntelliJ IDEA, 
                 PhpStorm, Appcode, etc. It was first introduced
                 by JetBrains in 2011.Kotlin is object-oriented 
                 language and a better language than Java, but still
                 be fully interoperable with Java code. A constructor
                 is a special member function that is invoked when 
                 an object of the class is created primarily to initialize
                 variables or properties. A class needs to have a constructor
                 and if we do not declare a constructor, then the compiler
                 generates a default constructor.
                 Kotlin has two types of constructors –
                 Primary Constructor
                 Secondary Constructor
                 A class in Kotlin can have at most one primary
                 constructor, and one or more secondary constructors. 
                 The primary constructor
                 initializes the class, while the secondary 
                 constructor is used
                 to initialize the class and introduce some extra logic.
                 Explanation:
                 When we create the object add for the class then 
                 the values 5 and 6
                 passes to the constructor. The constructor 
                 parameters a and b 
                 initialize with the parameters 5 and 6 respectively.
                 The local variable c contains the sum of variables. 
                 In the main, we access the property of 
                 contructor using ${add.c}.
                 Explanation:
                 Here, we have initialized the constructor 
                 parameters with some
                 default values emp_id = 100 and emp_name = “abc”.
                 When the object emp is created we passed the values for
                 both the parameters so it prints those values.
                 But, at the time of object emp2 creation, 
                 we have not passed
                 the emp_name so initializer block uses 
                 the default values and
                 print to the standard output.</string>
</resources>

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Step 3: Modify activity_main.xml 

Add the ScrollView and inside the ScrollView add a TextView to display the strings that are taken in the strings.xml file.

activity_main.xml

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<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
  
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:layout_editor_absoluteX="0dp"
        tools:layout_editor_absoluteY="-127dp">
  
        <TextView
            android:id="@+id/scrolltext"
            style="@style/AppTheme"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/scrolltext"
            android:textColor="@color/green"/>
    </ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>

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As already mentioned above, Scrollview can only contain one direct child. In this case, the child is textview. On noticing this textview you will realize that the text added inside textview is mentioned as @string/scrolltext which refers to a string resource inside the strings.xml file.

Step 4: MainActivity.kt file

There is nothing to do with the MainActivity.kt file, so keep it as it is.

MainActivity.kt

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package com.example.gfgapp_scrollview
  
import androidx.appcompat.app.AppCompatActivity 
import android.os.Bundle
  
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }
}

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Output: Run on Emulator 




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