Home > Articles > Mobile Application Development & Programming

This chapter is from the book

Hierarchy Viewer

Hierarchy Viewer is the unsung hero of layout optimization. It hasn’t seen a whole lot of change since the early versions, but it still remains a great go-to tool for figuring out what is happening with your layouts. It can be used for simply figuring out why a view doesn’t display or to figure out why a hierarchy is slow to load. It can even output your views as a PSD, allowing you to inspect positioning and colors with precision that is hard to match from simple screenshots.

If your device is running Android 4.0 (or lower) and is unlocked, everything should just work. If it’s running 4.0 (or lower) and it is locked, you can use the ViewServer class from Romain Guy (https://github.com/romainguy/ViewServer) in your app (be sure to add the internet permission). If your device is running Android 4.1 or newer, you need to set an environment variable called ANDROID_HVPROTO with a value of ddm. In Windows, you can open My Computer, Property, Advanced, Environment Variables, and click New to create it. For Mac you’ll open .bash_profile in your home directory (note that the file starts with a dot, which means it is hidden by default). Add a line that contains export ANDROID_HVPROTO=ddm and save the file. Now type source ~/.bash_profile from the command line (this causes the file to be re-read so that the variable is immediately set). For Linux, you can follow the same steps as for Mac but the file is .bashrc in your home directory.

Open Android Device Monitor (under the Tools menu and the Android submenu). The Hierarchy Viewer is a different perspective, so open the Window menu and click the Open Perspective option. Select Hierarchy View and click OK. If you haven’t already connected your device and opened the screen you want to inspect, do so now.

On the left side, you should see your device(s) listed. Select it and click the “Load view hierarchy” button (that’s the icon next to the refresh button; you can also click the downward-facing triangle and select the option there). If the icon is grayed out, that typically means there is an issue communicating with the device and more details should be available in the console (usually on the bottom right). If you’ve already followed the directions from two paragraphs ago and it’s still gray, you can also try closing out Android Studio (and anything else that might be communicating with the device) and then run Android Device Monitor directly (run monitor from the Android SDK tools directory).

Once the view hierarchy has loaded, the left window will show view properties, the center of the screen will be the detailed view hierarchy, the top right will be an overview, and the bottom right is the layout view that lets you see what portion of the screen the selected view is responsible for (the bottom right may be showing the console tab, so just click the Layout View tab). Your screen should look like Figure 10.11.

Figure 10.11

Figure 10.11 After the view hierarchy has been loaded, this is what you should see

Each gray box in the tree view (the center window) represents a view. The boxes can have the class type (e.g., LinearLayout), the memory address, the ID (e.g., id/content), performance indicators, and a view index. The view index shows you the view’s position within the parent, where the first child is position 0. The performance indicators are simply colored circles that indicate the time it took to measure the view, the time it took for the layout pass, and the time it took to draw the view. Newer versions of Hierarchy Viewer require you to click the icon with the three circles to obtain the layout times. These indicators on the gray boxes are broken into three groups. If a view is within the fastest 50% of views for the given indicator (e.g., draw time), that view will be green for that circle. If it’s in the 50% of slow views, it will be yellow. If it is the slowest of all the views, it is red. It’s important to realize these are relative indicators, so a view hierarchy that is extremely fast and efficient will still have a view with a red indicator for each circle just as an extremely slow hierarchy will.

By clicking a gray box, you can see an image of the view, a count of how many views this view represents (a 1 indicates the view itself; a 2 indicates the view plus a child view), and the exact times for measuring, laying out, and drawing the view. In the view properties (the left window), you can see virtually everything you could want to know about a view. This is extremely helpful when troubleshooting.

Finding Missing Views

One particularly handy use of Hierarchy Viewer is to figure out why a given view isn’t showing up. There are many different reasons a view might not appear on the screen, so being able to see all the view’s properties in one place plus a visual representation of the views in your hierarchy is incredibly useful. You can quickly see that a view’s alpha is 0 or its visibility is set to invisible. You can tell if the view was sized incorrectly or positioned incorrectly. Before Android was blessed with Lint checks, pretty much every developer at one point (or many points) would have a LinearLayout and some child views with their widths set to match_parent, run the app, and then wonder why only the first child showed up. Simple things like forgetting the default orientation is horizontal can leave you with unexpected results, but Hierarchy Viewer can easily show you where a view is positioned and seeing it on the right edge of the screen instead of below the previous view is usually enough to get the developer to realize the simple mistake.

Eliminating Unnecessary Views

The biggest benefit Hierarchy Viewer can bring is helping you understand the complexity of your view hierarchy and eliminate extra views. The more complex your hierarchy, the longer your UI thread has to lock up on measuring, laying out, and drawing your views. You should look for views that have only a single child because those are often extraneous views that are easy to remove. You should also look for several sibling TextViews because you can often consolidate them (details are later in this chapter). It’s a good idea to look for invisible views too. Although they aren’t drawn, views that have visibility set to INVISIBLE are still measured and even a view that is GONE will slow down your view lookups and take up memory. If you sometimes need some views on a given screen but not always, use a ViewStub instead of inflating the entire view hierarchy and not drawing it. It’s also a good idea to look out for views entirely outside of the screen (such as views that have been animated off the screen); it doesn’t do any good to waste processing power on something that will never be seen.

Exporting to PSD

One of the extremely powerful but often overlooked features of Hierarchy Viewer is the ability to export a layout hierarchy as a Photoshop Document (a PSD file). This can be hugely valuable to designers, so make sure they are aware of this functionality. There is a rather forgettable-looking button above the tree view that appears to be three overlapping squares. That’s the Capture Layers button. If you do not see it, you can also click the downward-facing triangle to get the list of options and select it from there. The resulting PSD can take a while to be generated, so be patient. If it fails, you will see an error in the console and can try again (occasionally it helps to reconnect the hardware device or restart the emulator).

Because this PSD is not using any advanced features such as layer masks, you can actually open it in GIMP and other tools as well. Along with the techniques discussed earlier in the chapter, this is an excellent method of detecting overdraw.

Exporting to a PSD is a great way for a developer and a designer to speak the same language. The designer can inspect in detail exactly what is going on with a layout by tweaking the layers and then tell the developer which layer has an issue (the layers are named after the view IDs when present, making it extra easy to associate a layer with a view). This also gives the designer the opportunity to make changes to further optimize the design. Perhaps initially a view seemed best at 50-percent opacity, but now the designer can tweak how opaque a view is just like any layer in Photoshop and determine that 40% is actually better.

One thing to note is that the layers are all rasterized. In simplistic terms, the pixels that each view creates are what are actually exported as layers. TextViews do not create actual Photoshop text layers, for instance. That also means that if you have a complex view that’s drawing shapes, text, and images, only the resulting pixels are exported, so you can’t see what each “layer” of that view looks like.

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.


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.


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.


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.


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


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


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.


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.


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