Jim Wilson (a.k.a. hedgehogjim)
30+ years as a professional software dev, 17+ years developing mobile solutions, Pluralsight Author, Founder JWHH, LLC
According to recent data, senior Android developers average $131,000 per year versus $121,000 for the same skill level on iOS.
That’s some pretty serious cash!
So what are you waiting for … clearly, it’s time to get your Android skills tuned up! 🙂
The full story is available in this Tech Week article.
Checkout Jim”s Android courses on Pluralsight.
Jim’s latest book, “Creating Dynamic UI with Android Fragments” is now available on amazon.
Part 4 of my four-part series on Android programming for developers with a .NET background just went live today.
This course delves into the unique features of the Android platform and how those features and the related components affect the way apps are created.
I hope you’ll check out this course and the whole series if you haven’t already seen it. I think you’ll be happy you did.
Here’s the complete series
Android Studio makes adding swipe navigation to your Android apps easy through the “Scrollable Tabs + Swipe” option of the Navigation Type selection in the New Project Wizard. Choosing this option works great as long as you have a static list of screens that the user “swipes” between.
The way swipe navigation works is that each screen is represented by an instance of a Fragment-derived class. These Fragment classes are then managed by a PagerAdapter-derived class which makes them, in effect, a scrollable list. Passing that PagerAdapter to a ViewPager presents that list in a way that the user can use a swipe-motion to move between screens.
The code generated by Android Studio provides a custom PagerAdapter class that derives from  FragmentPagerAdapter. Basically all one has to do is override the getItem method and return the desired Fragment for each screen position (you’ll also need to override getCount and getPageTitle but those are super simple). What happens though is that the FragmentPagerAdapter class is designed such that once a Fragment instance is returned for a given position that Fragment is permanently in that position. Once this happens, you can, of course, make changes to the contents of the Fragment but there’s no way to provide a different Fragment instance for that position which is often what’s necessary.
The comments in the generated class indicate that using FragmentStatePagerAdapter instead of FragmentPagerAdapter as the base class allows for more dynamic management of the Fragment instances. Reading the FragmentStatePagerAdapter documentation indicates that we can notify our FragmetStatePagerAdapter instance of a change in the list of screens (in other words that we’d like to use new Fragment instances) by calling the notifyDataSetChanged method. But that’s only part of the story.
Once you call this method what you’ll normally see is that screens that were previously visited still have the old Fragment instances but screens being visited for the first time have the new Fragment instances. If you have a large number of screens and scroll back and forth between them you may see some of the older screens eventually show a new Fragment instance.
Not really the consistent user experience we’re looking for 🙂
What’s happening is that FragmentStatePagerAdapter is trying to be efficient and only create new Fragment instances when necessary. To determine when to request new Fragment instances after a call to the notifyDataSetChanged method, FragmentStatePagerAdapter calls its getItemPosition method to see if an existing Fragment can be used in its current or possibly a different position without having to recreate it. What we have to do is tell the FragmentStatePagerAdapter instance that we don’t want to use the existing Fragment instance.
To do that we need to override getItemPosition as follows
public int getItemPosition(Object object) {
// Causes adapter to reload all Fragments when
// notifyDataSetChanged is called
return POSITION_NONE;
}
By returning POSITION_NONE we’re telling the FragmentStatePagerAdapter instance to discard that Fragment and just create new ones for every screen position.
To summarize what to do, here’s the list of steps…
And with that, you have the ease of swipe navigation with the ability to reload Fragments instances as needed
Adapted from Jim’s Pluralsight course Android for .NET Developers: Adopting the Android Mindset
Checkout Jim’s latest book: Creating Dynamic UI with Android Fragments
You’ve probably noticed that Android Studio doesn’t have a “clean” menu option. But we know that, like any build environment, there are intermediate files created that we may want to occasionally remove.
It turns out the solution is the command line. Simply open a command line in your project’s root folder (Usually named something like MyAppProject) and run the following command
gradlew clean
You’ll see something like this…
Notice that you get a bit of an unexpected message, “BUILD SUCCESSFUL”. This simply indicates that it has gone through and successfully cleaned out the intermediate files. I’ve found that when dealing with larger projects its not uncommon to reduce the amount of disk space used by the project by 70% or more.
So a bit of an unexpected solution (especially for those who’ve been in a Windows environment for a long time) but an easy one.
To learn more about Android programming, checkout Jim’s Android courses on Pluralsight.
Jim’s latest book, “Creating Dynamic UI with Android Fragments” is now available on amazon.
What I did on my Summer Vacation 🙂
It’s been a crazy busy Summer. Since May I’ve released 3 new Android courses for Pluralsight with a 4th coming out in a few weeks and wrote a book on Android Fragments titled Creating Dynamic UI with Android Fragments.
I’m excited to announce that the book just became available for pre-order today!!
I need to take a minute to thank my beautiful wife, Bonnie. As you might imagine, I’ve been putting in a lot of hours these past few months and would never have been able to get through it all without her. Her patience and support never end. Bonnie I love you!!
My life is so blessed, I can barely believe it.
Checkout this new trailer from Pluralsight showing off all of the great Android training content.
Android Studio 0.2.0 update … encountering issues with both new AND existing projects.
I’m fortunate that  using the latest and (sometimes not so) greatest is actually my job. With that I’ve been able to heavily use Android Studio ever since it was first released. To my knowledge, I’ve installed and heavily used every public update since the release.
Everyone of those updates went pretty smooth … until this one.
The switch to Android Studio 0.2.0 has, by far, been the bumpiest upgrade yet. After installing it…
Not much I can get done without being able to do one or the other. 🙂
The good news is that resolving these issues was pretty easy.
This issue appears to be specific to folks using Android Studio on Windows.
I initially let Android Studio handle the install as I had always done previously. Once the install completed, any attempt to create a new project resulted in the following error…
Basically, the message indicates that Android Studio can’t find a dependency.
The solution turned out to be that a fresh install is requried ….
And that took care of the problem
This turned out to be a two-fold problem for me.
The first issue has to do with a fairly well documented change that’s been made to Android Studio. They’ve changed to a new version of Gradle that’s not backward compatible. As a result an attempt to build a project that was created with a prior version of Android Studio shows the following error.
The fix is to change the version of Gradle that’s referenced in your project’s build.gradle file (located in top-level of project folder). If you click on the “Search in build.gradle files” link in the above dialog it’ll open the build.gradle file for you. Or you can just open the build.gradle file yourself. It’s quite small and easy to navigate.
To fix the problem simply change the line that reads
classpath ‘com.android.tools.build:gradle:0.4‘
to
classpath ‘com.android.tools.build:gradle:0.5.+’
This will cause Android Studio to use the required version of Gradle.
With that fix made, I would then get an error indicating
“FAILURE:Could not determine which tasks to execute”
The problem is related to extraneous entries that were added to the [ProjectName].iml file (in your project’s top-level folder) by earlier versions of Android Studio.
To fix the problem, exit Android Studio and open the [ProjectName].iml file in an editor and delete the entire component element with the name “FacetManager”.
This changes the file from…
<?xml version="1.0" encoding="UTF-8"?>
<module external.system.id="GRADLE" type="JAVA_MODULE" version="4">
<!-- *** Remove From here *** -->
<component name="FacetManager">
<facet type="android-gradle" name="Android-Gradle">
<configuration>
<option name="GRADLE_PROJECT_PATH" value=":" />
</configuration>
</facet>
</component>
<!-- *** To Here *** -->
<component name="NewModuleRootManager" inherit-compiler-output="true">
<exclude-output />
<content url="file://$MODULE_DIR$">
<excludeFolder url="file://$MODULE_DIR$/.gradle" />
<excludeFolder url="file://$MODULE_DIR$/build" />
</content>
<orderEntry type="inheritedJdk" />
<orderEntry type="sourceFolder" forTests="false" />
</component>
</module>
to
<?xml version="1.0" encoding="UTF-8"?>
<module external.system.id="GRADLE" type="JAVA_MODULE" version="4">
<component name="NewModuleRootManager" inherit-compiler-output="true">
<exclude-output />
<content url="file://$MODULE_DIR$">
<excludeFolder url="file://$MODULE_DIR$/.gradle" />
<excludeFolder url="file://$MODULE_DIR$/build" />
</content>
<orderEntry type="inheritedJdk" />
<orderEntry type="sourceFolder" forTests="false" />
</component>
</module>
And with that … SUCCESS!! Â … I’m now able to build the project without difficulty.
So the cleanup isn’t too difficult but does require some work. If you’re encountering issues other than those I’ve mentioned above the Android Studio folks have posted a couple of helpful pages addressing a variety of issues
To Learn more about Android programming, checkout Jim’s courses at Pluralsight.
The latest update to Android Studio, version 0.20 is now available.
You should be getting it automatically but if not just go to the Android Studio “Help” menu and choose “Check for Update…”
The list of updates and changes in this version can be found here.
Odds are that you’ve heard about the security hole that was found to exist in virtually all Android devices that would allow someone to take control of the device.
The good news is that Google has created a patch for the issue and sent it to OEMs. The challenge always comes down to the OEMs getting the patch distributed to our phones and, as always, that is taking time.
It turns out that we can all check to see if we have the patch installed thanks to Bluebox (the folks who discovered the problem) releasing a free app that will check your phone to see if you have the patch.
Although the app is not able to apply the patch because that’s up to the OEM of your device you can at least know where you stand and if you are so inclined start complaining to your carrier that you’d like them to work with the OEM and hurry to get it distributed.
Jim Wilson (a.k.a. hedgehogjim) 