1 page.title=Future-Proofing Your Apps 2 parent.title=Articles 3 parent.link=../browser.html?tag=article 4 @jd:body 5 6 <p>It's important to implement your application so that it will not break as new 7 versions of the Android platform are loaded onto the users device. The list 8 below is based on our observations of five ways that we've seen bad apps fail. 9 You can think of these as "anti-patterns" (that is, techniques to avoid) for 10 Android development.</p> 11 12 <p>If your application uses any of the dubious techniques below, break out 13 your IDE and duct tape, spackle, and patch up the app.</p> 14 15 <p><b>Technique to Avoid, #1: Using Internal APIs</b></p> 16 17 <p>Even 18 though we've always strongly advised against doing so, some developers 19 have chosen to use unsupported or internal APIs. For instance, many 20 developers are using the internal brightness control and bluetooth 21 toggle APIs that were present in 1.0 and 1.1. A bug -- which was 22 fixed in Android 1.5 -- allowed apps to use those APIs without 23 requesting permission. As a result, apps that used those APIs broke 24 on 1.5. If you've used internal APIs in your apps, you need to update 25 your apps to stop doing so. </p> 26 27 <p><b>Technique to Avoid, #2: Directly Manipulating Settings</b></p> 28 29 <p>Strictly speaking this one isn't evil, since this is a change in 30 behavior that we made to Android itself. But we made it because some 31 developers were doing naughty things: a number of apps were changing 32 system settings silently without even notifying the user. For instance, 33 some apps turn on GPS without asking the user, and others might turn on 34 data roaming.</p> 35 36 <p>As a result, applications can no longer directly 37 manipulate the values of certain system Settings, even if they 38 previously had permission to do so. For instance, apps can no longer 39 directly turn on or off GPS. These apps won't crash, but the APIs in 40 question now have no effect, and do nothing. Instead, apps will need to 41 issue an Intent to launch the appropriate Settings configuration 42 screen, so that the user can change these settings manually. For 43 details, see the android.provider.Settings.Secure class, which you can 44 find in the 1.5_pre SDK documentation (and later). Note that only 45 Settings that were moved to the Settings.Secure class are affected. 46 Other, less sensitive, settings will continue to have the same behavior 47 as in Android 1.1.</p> 48 49 <p><b>Technique to Avoid, #3: Going Overboard with Layouts</b></p> 50 51 <p>Due to changes in the View rendering infrastructure, unreasonably deep 52 (more than 10 or so) or broad (more than 30 total) View hierarchies in 53 layouts are now likely to cause crashes. This was always a risk for 54 excessively complex layouts, but you can think of Android 1.5 as being 55 better than 1.1 at exposing this problem. Most developers won't need to 56 worry about this, but if your app has very complicated layouts, you'll 57 need to put it on a diet. You can simplify your layouts using the more 58 advanced layout classes like FrameLayout and TableLayout.</p> 59 60 <p><b>Technique to Avoid, #4: Bad Hardware Assumptions</b></p> 61 62 <p>Android 1.5 includes support for soft keyboards, and there will soon be many 63 devices that run Android but do not have physical keyboards. If your 64 application assumes the presence of a physical keyboard (such as if you 65 have created a custom View that sinks keypress events) you should make 66 sure it degrades gracefully on devices that only have soft keyboards. 67 For more information on this, keep on eye on this blog as we'll be 68 posting more detailed information about handling the new soft keyboards.</p> 69 70 <p><b>Technique to Avoid, #5: Incautious Rotations </b></p> 71 72 <p>Devices running Android 1.5 and later can automatically rotate the screen, 73 depending on how the user orients the device. Some 1.5 devices will do 74 this by default, and on all others it can be turned on by the user. 75 This can sometimes result in unpredictable behavior from applications 76 that do their own reorientations (whether using the accelerometer, or 77 something else.) This often happens when applications assume that the 78 screen can only rotate if the physical keyboard is exposed; if the 79 device lacks a physical keyboard, these apps do not expect to be 80 reoriented, which is a coding error. Developers should be sure that 81 their applications can gracefully handle being reoriented at any time.</p> 82 83 <p>Also, apps that use the accelerometer directly to reorient themselves 84 sometimes compete with the system doing the same thing, with odd 85 results. And finally, some apps that use the accelerometer to detect 86 things like shaking motions and that don't lock their orientation to 87 portrait or landscape, often end up flipping back and forth between 88 orientations. This can be irritating to the user. (You can lock your 89 app's orientation to portrait or landscape using the 90 <code>android:screenOrientation</code> attribute in the manifest file.)</p> 91 92
