Home > Articles > Mobile Application Development & Programming

This chapter is from the book

Loading Indication

Immediate feedback is one of the most important parts of a good UI. If a button does not have a touch state and the resulting action takes some time, the user will feel like the app is unresponsive. Unfortunately, whether the app needs to run complex image analysis algorithms or just access web resources, there are times when it will not be able to immediately show the users what they want to see. In these instances, you use a loading indicator to give the user a sense that something is happening. Ideally, you use a loading indicator that can show progress such as when downloading a file, but sometimes you have to fall back on the indeterminate loading indicator, which just tells the user, “Hey, something is happening, but who knows how long it will take.”

Dialogs versus Inline

Using dialogs to indicate loading is the go-to solution for a lot of developers. In fact, Android’s ProgressDialog class makes this extremely easy. Just create an instance using one of the static show() methods and then update it if possible. When your task is done, you just dismiss() the dialog. Simple enough, right?

The problem is that these dialogs are modal. That means the user can do nothing else in your app while looking at one of these dialogs, so they don’t make sense unless there really is nothing else the user can do (for example, the previously explained splash screen). You may have allowed the user to back out of the dialog, but that just results in the user being confused as to whether the task actually stopped or not (and further confused when the UI suddenly changes when it does complete). Instead, consider using inline loading indicators.

An inline loading indicator is basically a loading indicator that is a part of your regular view hierarchy. It goes where the content that is loading will go and serves as a placeholder as well as a visual indication of activity. Not only is this significantly less disruptive than a dialog, it lets the user interact with other content immediately. If you go to Google Play to search for a particular app, you don’t want to wait while the front page loads before you can actually search. An additional advantage of inline indicators is that they allow you to load different sections of a screen and display them independently. You might go to someone’s profile page in an app and see the basic info. At the same time, one section is loading that displays recent content posted by that person and another section loads people who are similar to that person. Neither of these pieces is dependent on the other.

Using an Inline Loading Indicator

Using inline loading indicators in your app is actually extremely easy. The simplest way is to just include a ProgressBar in your layout somewhere and then hide or remove it when the loading is complete and add the new views. There are several ways to make this easier to manage. If the extra content is almost always available (for example, you might go from a list of articles to a detailed article page, and you just need to fetch the body text), then an easy approach is to use a ViewSwitcher. A ViewSwitcher is a ViewGroup that contains two child Views and can animate between them. In this case, you use it to display a loading indicator and then switch to the other View when it is ready.

First, define a couple of animations in XML. These go in res/anim. Listing 10.6 defines a simple fade-in animation, and Listing 10.7 defines a fade-out animation.

Listing 10.6. A Simple Fade-in Animation Saved as fade_in.xml

<?xml version="1.0" encoding="utf-8"?>
<alpha xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="300"
    android:fromAlpha="0.0"
    android:interpolator="@android:anim/decelerate_interpolator"
    android:toAlpha="1.0" />

Listing 10.7. A Simple Fade-out Animation Saved as fade_out.xml

<?xml version="1.0" encoding="utf-8"?>
<alpha xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="300"
    android:fromAlpha="1.0"
    android:interpolator="@android:anim/accelerate_interpolator"
    android:toAlpha="0.0" />

With those animations defined, all you need now is a ViewSwitcher that is displaying a loading indication and a second child View that is the content you have finished loading. You set the animations and then simply call showNext(), as shown in Listing 10.8.

Listing 10.8. Using a ViewSwitcher to Animate Between Views

ViewSwitcher viewSwitcher = (ViewSwitcher) findViewById (R.id.view_switcher);
viewSwitcher.setInAnimation(this, R.anim.fade_in);
viewSwitcher.setOutAnimation(this, R.anim.fade_out);
viewSwitcher.showNext();

Sometimes you’ll have some chunk of content that is frequently not there or that has a complex view hierarchy. In these cases, it’s a good idea to make use of ViewStubs. A ViewStub is an extremely simple implementation of View that essentially acts as a placeholder for other content. It takes up no space and draws nothing, so it has minimal impact on your layout complexity. Think of it like an include tag that does not actually include another layout until you say to do so.

Listing 10.9 shows what a ViewStub will look like in your XML layout. The regular ID is used for finding the ViewStub, but it can also specify an inflatedID for finding the layout after it has been inflated. The layout that will be inflated is specified by the layout property the same as it is in an include tag.

Listing 10.9. An XML ViewStub

<ViewStub
    android:id="@+id/view_stub"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:inflatedId="@+id/dynamic_content"
    android:layout="@layout/other_layout" />

All that is left to do is to find a reference to your ViewStub, inflate it, and do whatever you need to with the resulting layout. See Listing 10.10 for the basic code involved.

Listing 10.10. Inflating a ViewStub in Java

ViewStub stub = (ViewStub) findViewById(R.id.view_stub);
View otherLayout = stub.inflate();
// Do something with otherLayout...

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020