rxjava RxJava's repeatWhen and retryWhen, explained repeatWhen [http://reactivex.io/RxJava/javadoc/rx/Observable.html#repeatWhen(rx.functions.Func1)] and retryWhen [http://reactivex.io/RxJava/javadoc/rx/Observable.html#retryWhen(rx.functions.Func1)] are fairly baffling at first glance. For starters, they are serious contenders for "most confusing marble diagrams": They're useful
android Making EditTexts with links both clickable and editable Recently, I was working on an EditText [http://developer.android.com/reference/android/widget/EditText.html] that supports links. That is, users can add URLs that become clickable when not editing. When the EditText is not focused, the links should be clickable. However, when it is focused, it should disable
rxjava Error handling in RxJava RxJava makes error handling a snap. Just use onError, right? That's fine and dandy if you're the subscriber, but what about exceptions that occur inside your operators? How do you ensure that an Exception in, say, flatMap() gets passed along to onError? And what if you
android My First Android App, Six Years Later Allow me to indulge in a bit of throw-back-Thursday reminiscing as I look back on my first ever Android app: FlightTrack. In October of 2009 I joined a small travel app startup, Mobiata, and was tasked with writing the Android version of its already successful iOS app FlightTrack. The deadline
android Sharing code between unit tests and instrumentation tests on Android Edit (August 16, 2022): This method is outdated and no longer works on the latest versions of Android Studio. See my new guide for an up-to-date solution on this problem. Suppose you've got an Android application with a bunch of tests. Some of them are unit tests (located
android Using hardware layers to improve Android animation performance When someone asks me about poor animation performance, one of the first questions I ask is whether or not they are using hardware layers. During animations your views may be redrawn each frame. If you use view layers, instead of having to redraw each frame, views render once into an
android Beware EditText on API 21 Check out these two EditTexts. One is on an API 21 device, the other on an API 22 device. See the difference? It's even more pronounced with "show layout bounds" enabled: The height and vertical alignment of the EditTexts are different! This was caused by a
android Sharing files on Android in a world with runtime permissions There are some growing pains we're going to experience while upgrading to runtime permissions. The most painful one I've run into so far is sharing files. When done correctly, sharing a file involves a sender app creating an accessible URI and a receiver app reading a
android Don't use dynamic versions for your dependencies Everyone, please, to stop using dynamic versions for your dependencies. In Gradle, dynamic versions use the + sign like so: compile 'com.android.support:appcompat-v7:23.0.+' Ideally, your builds should be predictable and consistent. Identical source code should yield the same result, every time you build. Dynamic versions
android How to upgrade to RxAndroid 1.0 A number of people have asked me recently, "What the hell happened to RxAndroid [https://github.com/ReactiveX/RxAndroid]?" The fact of the matter is, RxAndroid was getting to be a bit of a mess and thus has been majorly refactored. You can read more about it here
rxjava Deferring Observable code until subscription in RxJava I've grown fond of RxJava's defer() [http://reactivex.io/documentation/operators/defer.html] as a tool for ensuring Observable code runs when subscribed (rather than when created). I've written about defer() before [http://blog.danlew.net/2014/10/08/grokking-rxjava-part-4/#oldslowcode] but I'
rxjava Loading data from multiple sources with RxJava Suppose I have some Data that I query from the network. I could simply hit the network each time I need the data, but caching the data on disk and in memory would be much more efficient. More specifically, I want a setup that: 1. Occasionally performs queries from the
android Recent presentations and code I've been quite busy in the past several months! Talk: An Introduction to Groovy and Gradle I had been using Gradle-based Android builds for a long time before actually bothering to try to understand what's going on in them. This talk will help get you started
android Lessons learned from our first Gradle plugin for Android, Victor The Android team at Trello is happy to announce our first open source Android library, Victor [https://github.com/trello/victor]! It's a Gradle plugin that lets you use SVGs as resources in your Android apps. Victor started as a request from our designers. They were regularly creating
android Is your user a goat? Last updated August 17, 2015 Android isn't always serious business. Here are some of the sillier parts of the Android SDK. Useful The following do real things but have amusing names. FEATURE_TOUCHSCREEN_MULTITOUCH_JAZZHAND [http://developer.android.com/reference/android/content/pm/PackageManager.html#FEATURE_TOUCHSCREEN_MULTITOUCH_
android Pseudolocalization: Visiting Android's Bizarro World I wrote a while ago about pseudolocalization on Android [https://blog.danlew.net/2014/04/16/android-localization-tips/] but times have changed and I wanted to give an update. Pseudolocalization [http://en.wikipedia.org/wiki/Pseudolocalization] is a developer testing method that automatically translates your strings files into gibberish, with extra
rxjava Don't break the chain: use RxJava's compose() operator One nice aspect of RxJava is that you can see how data is transformed through a series of operators: Observable.from(someSource) .map(data -> manipulate(data)) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(data -> doSomething(data)); What if you have a set of operators that you
android Setting up a new app in Crashlytics without the IDE plugin I like Crashlytics [https://crashlytics.com/]. I like the service they provide: their crash logs have saved my ass countless times. I also like that it's free. However, there is one problem I've run into time and time again: getting new apps setup with it. They
android A Guide to Lollipop Notification Settings Lollipop changed the notification settings we all knew and loved but in a rather unintuitive way. It's so unintuitive I felt the need to write this guide. In short: you can do (almost1) everything you used to be able to do and more! It's just confusing
android Handling Android resources with non-standard formats In Android you have to deal with a large variety of screen sizes. The current solution is to use adaptive design to handle all the screens. One concept of adaptive design is that you have ever-growing content frames... up to a point. Once the device is too large or wide,
android An animated drawable issue in Lollipop A common pattern in Android is to use View.setVisibility() to swap widgets in your hierarchy. Unfortunately, in Lollipop, there is a risk of running afoul of the new RippleDrawable [https://developer.android.com/reference/android/graphics/drawable/RippleDrawable.html] when doing so. Let's look at a sample
android I don't need your permission! Permissions on Android are tricky to get right from a user perspective. Usually you only want to do something minor and innocuous (pre-fill a form with a contact's info) but the actual permission you have to request gives you much more power than necessary (access to ALL contact
android Styling Views on Android (Without Going Crazy) Styles are hard to get right on Android. There's a lot of potential for frustration. The hierarchy easily devolves into spaghetti code. How often have you wanted to change a style but feared you might break something unintentionally by doing so? After many years of working with Android,
You Should Write More How often does this happen to you: Your program crashes with a mysterious exception. You paste the crash logs into Google. The first link has a solution. Hooray! You found this magical solution because some good samaritan in the past decided to share his or her notes. You, too, can
android Grokking RxJava, Part 4: Reactive Android In parts 1 [https://blog.danlew.net/2014/09/15/grokking-rxjava-part-1/], 2 [https://blog.danlew.net/2014/09/22/grokking-rxjava-part-2/], and 3 [https://blog.danlew.net/2014/09/30/grokking-rxjava-part-3/] I covered how RxJava works (in a general sense). But as an Android developer, how do you make it work
