Scrolling activity android studio

ScrollView и HorizontalScrollView

При большом количестве информации, которую нужно поместить на экране приходится использовать полосы прокрутки. В Android существуют специальные компоненты ScrollView и HorizontalScrollView, которые являются контейнерными элементами и наследуются от ViewGroup. Обратите внимание, что класс TextView использует свою собственную прокрутку и не нуждается в добавлении отдельных полос прокрутки. Но использование отдельных полос даже с TextView может улучшить вид вашего приложения и повышает удобство работы для пользователя.

На панели инструментов компоненты можно найти в разделе Containers.

В контейнеры ScrollView и HorizontalScrollView можно размещать только один дочерний элемент (обычно LinearLayout), который в свою очередь может быть контейнером для других элементов. Виджет ScrollView, несмотря на свое название, поддерживает только вертикальную прокрутку, поэтому для создания вертикальной и горизонтальной прокрутки необходимо использовать ScrollView в сочетании с HorizontalScrollView. Обычно ScrollView используют в качестве корневого элемента, а HorizontalScrollView в качестве дочернего. Можно и наоборот, пробуйте.

В в теле метода onCreate() создайте ссылку на элемент TextView, объявленный в XML-разметке, и запишите в него через метод setText() какой-нибуль длинный текст, который не поместится в видимые размеры экрана устройства:

Запустив проект, вы должны увидеть вертикальную и горизонтальную полосы прокрутки при попытке скролирования.

Если полосы прокрутки вас раздражают, то используйте атрибут android:scrollbars=»none», который скроет их.

По такому же принципу можете вложить ImageView, чтобы просматривать большие картинки:

Методы scrollBy() и scrollTo()

Вы можете программно прокручивать контент с помощью методов scrollBy() и scrollTo(). Например, можно организовать автоматическую прокрутку во время чтения. В нашем примере мы будем прокручивать контент с помощью трёх кнопок.

Сам код для методов:

Дополнительное чтение

Библиотека ParallaxScrollView с использованием эффекта параллакса. Вы прокручиваете длинный текст, а задний фон прокручивается чуть медленнее. Возможно, кому-то пригодится. Там же можно скачать готовое демо и просмотреть в действии.

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Android ScrollView,NestedScrollView,HorizontalScrollView etc

In this piece we want to look at several scrollview variations or subclasses and how they are used. Here are the variations we cover so far:

1. ScrollView – Superclass
2. NestedScrollView – child class
3. HorizontalScrollView – child class
4. StickyScrollView – Child class and third party library.
5. ParallaxScrollView – child class and third party library

1. ScrollView

Android ScrollView Tutorials and Examples

A ScrollView is an android layout that permits it’s child views to be scrolled vertically. This is important because in many cases you need content to be scrolled. Normally adapterviews like ListView and recyclerview have scrolling capability but not many views. Hence we don’t use scrollview with them otherwise we get degraded performance.

With scrollview you only scroll up or down. However if you want horizontal scrolling then you can use the HorizontalScrollView.

Furthermore, ScrollView should only have one direct child. This then means that if you desire to add multiple children then use a ViewGroup like relativelayout or LinearLayout. Then add those children to the viewgroup and the viewgroup to Scrollview.

Android Engineeres are recommending that you use NestedScrollView instead of ScrollView for vertical scrolling.

This is because the latter offers greater user interface flexibility and support for the material design scrolling patterns.

ScrollView API Definition

A scrollview as a class resides in the android.widget package and derives from FrameLayout:

Here’s the inheritance hierarchy of FrameLayout:

Important ScrollView methods

(a). scrollTo(int x, int y)

In this method you pass the scrolled position of your view. This version also clamps the scrolling to the bounds of our child.

(b). smoothScrollTo(int x, int y)

Like scrollTo(int, int) , but scroll smoothly instead of immediately.

(c). getChildAt(int index)

This method will return the view at the specified position in the group.

(d). getChildCount()

This method returns the number of children in the group.

Quick ScrollView Examples

1. ScrollView – How to Scroll to the Top

Let’s see how you can scroll to the top of your scrollview.

2. How to Scroll to Down in ScrollView

Then we want to see also how we can scroll down to the bottom of our scrollview programmatically.

It’s a static method and we pass ScrollView instance as a parameter. First we get the height of the scrollview as we as it’s child counts.

At the end of the day we are still using the scrollTo() method, passing in the x and y positions.

3. How to smooth scroll to up

We use the smoothScrollTo() method and pass the positions.

4. How to smooth scroll to Down

Here’s how we can scroll to down programmatically.

5. How to calculate height of ScrollView by Child View

6. How to create a scrollview with maximum height limit

What if we desire to set the maximum height limit to our scrollview. Well we can simply create a custom scrollview by deriving from the android.widget.ScrollView class, override our constructors as well as the onMeasure() method.

7. Full ScrollView Example

Let’s look a full scrollview example.

(a). MainActivity.java

(b). activity_main.xml

2. NestedScrollView

Android NestedScrollView Tutorials and Examples.

NestedScrollView is a ScrollView that is able to act as a nested scrolling parent and child on both new and old versions of Android.

Nested scrolling is enabled by default in NestedScrollView.

NestedScrollView is recommended in many cases over ScrollView.

This is due it’s ability to offer greater user interface flexibility and support for the material design scrolling patterns.

NestedScrollView API Definition

NestedScrollView was added in android version 22.1.0 and belongs to Maven artifact com.android.support:support-compat:latest_version .

Like ScrollView, nested scrollview derives from FrameLayout.

However it goes further and implements three scrolling interfaces:

1. NestedScrollingParent – an interface implemented by [ViewGroups(/android/viewgroup)] that wish to support scrolling operations delegated by a nested child view.
2. NestedScrollingChild2 – an interface implemented by View subclasses that wish to support dispatching nested scrolling operations to a cooperating parent ViewGroup.
3. ScrollingView – An interface that can be implemented by Views to provide scroll related APIs.

Here’s the inheritance hierarchy for nestedscrollview:

You can find complete API reference in android developer documenattion.

Quick NestedScrollView Examples

1. How to Calculate NestedScrollView Height by it’s child view

HorizontalScrollView

Android HorizontalScrollView Tutorial and examples.

A HorizontalScrollView is a Layout container for a view hierarchy that can be scrolled by the user, allowing it to be larger than the physical display.

You use HorizontalScrollView, as the name suggests, to scroll horizontally. If you want to scroll vertically then you can use ScrollView or even better NestedScrollView.

All these «ScrollViews», HorizontalScrollView included, derive from the FrameLayout.

Hence you should strive to place only a single child. Then that child can have multiple other views.

Alot of people love using LinearLayout with horizontal orientation. Thus providing a nice and easy way of showing and then scrolling through views arranged nicely horizontally.

Beware that some views are capable of handling their own scrolling. Such is the textView. So it doesn’t require HorizontalScrollView.

HorizontalScrollView API Definition

HorizontalScrollView was added in API level 3 so is actually than you might think.

We said it derives from FrameLayout

Here’s it’s inheritance tree:

HorizontalScrollView Examples

4. StickyScrollView

StickyScrollView is a library that provides you with a scrollview with a custom header and footer. It is really ideal for showing details, for example product details. As you may know scrollview is a layout that permits its children to be scrolled.

Well StickScrollview provides you with the same capability as scrollview but allows you to add a header and footer.

StickyScrollView is written in Java and extends ScrollView class:

Installation

StickScrollView is hosted in Maven jitpack so to install first go to your root level build/gradle and register jitpack as a repository:

Then you add it as a dependency:

How to Use it

Well its a layout so its usage is very simple:

Full Example

Well first install as instructed above. Then make sure your minimum API level is API 16 or above.

(a). activity_main.xml

(b). MainActivity.java

First add your imports, including the StickyScrollView library:

Then create your activity class:

Define StickyScrollView as an instance field:

Reference views in your onCreate() method:

Now handle click events:

Here is the full code:

Here is the demo:

Special thanks to @amarjain07 for this awesome library and example.

5. Parallax Scroll

Android Paralax Scroll Library Tutorial and Example.

ParallaxScroll is a library that provides us with Parallax ScrollView and ListView for Android.

ParallaxScroll enriches us with these special adapterviews:

1. ParallaxListView.
2. ParallaxExpandableListView.
3. ParallaxScrollView.

This library was created by Nir Hartmann.

The library has existed for more than 5 years and is still actively maintained. It also has examples which we will explore later on.

ParallaxScroll supports Android 1.6 and above.

Android Parallax Scroll

See the demo app at Google Play here.

ParallaxScrollView internal Details

Let’s explore the internal specifics of Parallax before jumping to usage examples. We want to see the several classes from which the library is built so that we can even extend.

(a). ParallaxScrollView

This is class that internally derives from ScrollView.

You all know that a scrollview is a Layout container for a view hierarchy that can be scrolled by the user, allowing it to be larger than the physical display.

Like most View resources, ParallaxScrollView exposes three public constructors:

(a). ParallaxListView

ParallaxListView derives from the ListView class:

It also has three constructors we can use to create it’s instance:

It goes ahead and exposes us some methods we can use apart from the normall ListView methods:

(c). ParallaxExpandableListView

ParallaxExpandableListView adds parallax scroll to an ExpandableListView from which it derives.

This class provides us two constructors for object creation:

Here are some of the methods we can use apart from those we derive from ExpandableListView.

Installing ParallaxScroll

You can install ParallaxScroll from it’s maven repository via gradle.

All you need in android 1.6 and above. Then you add the following implementation statement in your app level build.gradle:

Then you sync the project to add the library files into your project.

Using ParallaxScroll

Let’s say you want to use a ScrollView , then you can add the following in your layout.

In that case we’ve used a ParallaxScrollView and placed inside it a LinearLayout with Text content that will be scrolled.

Well you can also add a ParallaxListView and ParallaxExpandableListView in your layout.

Full ParallaxScroll Examples.

Here’s an example.

1. Single Parallax ListView example.

Let’s start by looking at a our SingleParallaxListView example.

(a). CustomListAdapter.java

We start by writing our adapter class. It will derive from BaseAdapter.

(b). SingleParallaxListView.java

This is our activity class. This activity will contain our ParallaxListView.

(c). list_one_parallax.xml

You can see this is the layout that will be inflated into our SingleParallaxListView .

2. Multi Parallax ListView example.

We are using the CustomListAdapter we had already defined.

(a). MultipleParallaxListView.java

(b) list_multiple_parallax.xml

Single Parallax ScrollView Example

Let’s now look at single parallax scrollview example.

(a). SingleParallaxScrollView.java

(b) scroll_one_parallax.xml

4. SingleParallaxAlphaScrollView Example

(a) SingleParallaxAlphaScrollView.java

(b) scroll_one_parallax_alpha.xml

SingleParallax ExpandableListView Example

(a) CustomExpandableListAdapter.java

(b) SingleParallaxExpandableListView.java

(c) expand_list_one_parallax.xml

You can get full source samples below:

Download

Also check our video tutorial it’s more detailed and explained in step by step.

No.	Location	Link
1.	GitHub	Direct Download
2.	GitHub	Library
3.	Google Play	Demo App

Credit to the Original Creator @nirhart

How to Run

1. Download the project.
2. Go over to sample folder and edit import it to your android studio.Alternatively you can just copy paste the classes as well as the layouts and maybe other resources into your already created project.
3. Then edit the app level build/gradle to add our dependency as we had stated during the installation.

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