support multiple OS versions incrementally - android

I'd like to support Android 2.1 devices, but also would like to enable users to move my app to the SD card if they have Android 2.2+
The attribute for that is android:installLocation="auto"
How can I still support 2.1 while enable this attribute for 2.2+?
EDIT: I've set it with build 2.1 and I get a compilation error and I cannot launch my app. The reason I don't want to increase the build target to 2.2 is because if I do that and the app gets installed on 2.1, a bunch of exceptions are thrown and it crashes. I want to make sure that the app works perfectly on 2.1. For an example of what I mean, please see NoSuchMethodError: String.isEmpty

An exact solution for you is in Android Manual.

It can be done, set your minimum API level to 7 and your target API level to 8, more details are in the Dev Guide.

Related

Xamarin Forms App crashing on Huawei P20 Pro

I've built an app that successfully runs on all sorts of Android devices. It was compiled for Android 8, but the device it's running on is Android 9.
Every time I open it on this Huawei P20 Pro, I get a crash. The only sensible error I can see is:
No implementation found for android.content.Context md5c497ac42f3138c67aed930c79af470d4.MainApplication.n_getApplicationContext() (tried Java_md5c497ac42f3138c67aed930c79af470d4_MainApplication_n_1getApplicationContext and Java_md5c497ac42f3138c67aed930c79af470d4_MainApplication_n_1getApplicationContext__)
I never call the get Application Context at any point, so I'm really not sure what is going on here.
Any helpful tips on debugging an issue like this?
If you compiled it with SDK 27 as max API (version 8) why would you run it on SDK 28, Compile with max version available 28 or 29 and then try running
In manifest make it android:targetSdkVersion="28" and compile using latest
First of all, I believe that the issue lacks enough details to make any assumptions about the possible causes. One of the possible causes is setting the target SDK version incorrectly. You can attempt to set to a correct one for the app as Ross Vernal suggested. It may can solve your problem.
Based on what I read from the official Android documents about the targetSdkVersion property, setting the version lower than the API level of a mobile device means that some additional compatibility behavior may be required when the app runs.
But this does not mean that the app cannot run on the devices with higher API levels. Whether the compatibility behavior is required depends on the app itself.
Therefore, it's possible that a feature or something else that you have decided to use in your app caused the issue on the device.
Additionally, I tested these conditions on my Huawei device that runs on Android 9 (SDK 28) with a sample Xamarin.Forms app under a target SDK of 27.
The app launched successfully. This supports the possibility mentioned above.

Relation between android version of device and version specified in the app

While creating a project using eclipse i have Minimum SDK required as Android 2.2(Froyo) and Target SDK as Android 4.2(Jelly Bean) compile with Android 4.3. I have used sqlitebrowser v2.ob1 for creating database. My app runs without any errors (few lines in red in logcat though) and meets my requirements when i run it in an emulator. I tried 3 different emulators and it works fine. But when i tried this app in a mobile device it shows force close whenever there is something to do with database. I mean to say that it shows force close when it has to retrieve from database or connect to database. By searching i learned that just the .apk file is enough for the app to run even if externally created database is used in it (copying to assets folder and then to the default location). My questions are
Shouldn't my app work fine in any device ranging from Android 2.2 to 4.2 ?
Should i try compiling the app with Android 4.2 instead?
Am not sure about the version of the device i tried it in but am sure its within 2.2 and 4.2 . (Probably gingerbread). Other than plugging the device to PC via USB and seeing logcat (bcoz i dont own an android mobile phone) what can i do to solve this?
How is the app's version, emulator and version of mobile or any other device related?
My app can run on what versions of devices?
This is my first android app so any help is appreciated. Thanks in advace
It's possible that you are using a feature in your application that isn't supported by a lower version of the SDK. It's difficult to tell you exactly what that might be without any source code or stacktrace, but I can clear up your understanding of minSdkVersion and targetSdkVersion.
Consider that with each new version of the Android SDK, additional features and APIs are introduced that did not exist in previous versions. Obviously, the older versions of Android don't support those features.
When you specify a targetSdkVersion you are specifying that you are using features that were introduced in that particular version of Android. You are also implying that you have tested your application at that particular API level, and that it works as it should.
When you specify a minSdkVersion that is lower than your targetSdkVersion, you are implying that your application will work properly on a lower API level because you have manually programmed tests or checks in your code to ensure that the current API level is compatible with a feature before running it.
For example, if I wanted to run a feature introduced in Jelly Bean but I want to retain support for a lower API level (e.g. Gingerbread), I might add the following check before I run the feature (see other version codes here):
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
// run some code specific to API level 16
}
The Android SDK can automatically deal with code introduced in a lower API level, but it can't automatically deal with code specific to a higher API level.
So with that in mind, to answer your questions:
No, it's only guaranteed that your application will work properly on Android 4.2. It's up to you to ensure that it remains backwards compatible for earlier versions that you wish to support.
It shouldn't matter. Instead, you should first determine if your application runs on a device/emulator that is running the same API level as you are targeting (Android 4.2, API level 17), then run it on a device/emulator running a lower version and try to isolate the code that is causing it to crash (logcat will be helpful).
You can check the Android version of a device by going into Settings > About phone > Android version. If it is running Gingerbread, keep in mind that a lot of new features have been introduced since then and your application might be using some of those features. For the emulator, you can specify an API level when you create an emulator (you can download other versions to use from the SDK Manager).
I think my answer so far has made this relationship clear.
To reiterate, your application WILL run on any device running Android 2.2 or later, but it can crash if you are using features from a higher API level than the device is running.
If this is still not clear, you should read more about supporting multiple platform versions in the Android documentation: here.

Android build target

I've been writing my first android app and so far have just been building against the highest android SDK available - 4.1. Up until this point I have only been testing on a physical device running 4.03 and everything seems to work fine.
I would like my min SDK level to be level 8 (2.2) and as far as I know I have not used anything from the APIs higher than this.
However if I build against 4.1 and run on a 2.2 emulator it just shows a white screen and no crash (OpenGL based so something going wrong with this). The same build runs fine on a 4.1 emu and my 4.03 device.
If I build against 2.2 with the exact same code it runs on the 2.2 emu fine.
I don't really know what could be causing this so any tips would be great. Do some classes get replaced in the newer APIs? If they were removed entirely I would assume it just wouldn't build at all against the new version.
Should I be setting my build target equal to my minimum? I am not using anything from the APIs higher than 2.2 currently but I was under the impression I should be building against the newest SDK available. Are there any negative effects of building for the lowest version for instance does it affect the look of the menus/dialogs?
Any help is appreciated, thanks.
You should build against the lowest SDK version you intend to be supported by your app (e.g., if you want to support users don't having the newest smart phones or tablets, building against the newest SDK version wouldn't be a good idea).
Generally, newer SDK versions only include additional classes and functions, but I am not 100% sure about any removed classes.
add this to your AndroidManifest.xml
<uses-sdk
android:minSdkVersion="7"
android:targetSdkVersion="15" />

Compiling with Android 4.X but supporting API Level 9

I'm working on an application which uses ActionBarSherlock. As it's documentation points out:
[...] the library requires that both it and your project are
compiled with Android 4.0 or newer. The project also requires that
you are compiling with JDK 1.6 in both your editor and any build
systems that you may be using.
So, that means I'll compile my application (and the library) against Android 4.X but in my Manifest, I declare that I'm targeting (e.g.) API Level 9.
This all works fine and well but there is something that disturbs me. From the FAQ:
What API level should I target in my manifest when using the library?
Targetting API level 11 or newer is required as it will cause Android
to automatically add the native action bar when run on newer devices.
Since you will be compiling against new APIs but your app will likely
be run on devices with older versions of Android extra care must be
taken to either avoid using or properly check and call any methods
that were introduced after your minimum SDK version.
That means, that I'll have to manually check every method call, so I don't use any that are not available in my targeted API Level (9 in my case)? This sounds wrong to me.
Is there a way to tell my IDE (IntelliJ), that I'm only using the API Level 9 (so I don't get any auto-completion for non-existing methods/classes and don't use them by accident) and then choose to compile it against another Android version?
Or can I use some automated checks (which run at compile time) to check for that?
The ADT's lint feature should take care of this by warning when API calls are being made for the wrong API version.
You should be compiling both ABS and your project with the latest SDK available (at present, 4.1). Your manifest should have a targetSdkVersion as high as possible (ideally matching your compilation SDK) and your minSdkVersion should be set to the lowest version you support.
Lint is partially integrated with IntelliJ IDEA and is also available as a command line tool.
You temporarily set your target SDK to the various lower ones and debug with it. Your final build then is with the latest SDK.
Set a Build target similar to that you have mentioned in your manifest.
as always , you should set the targetSdk to the maximum available on both the manifest and the project.properties file (as recommended by google on one of their videos) , so that the ADT&SDK would be able to optimize the ADK accordingly.
set the minSdk to the one that you wish to support your app from , and let Lint to tell you if there are any problems in case you use too-new-features.

What happens if we use/install 2.3 build in 2.2 device

I am working on application which should go into android 2.2(Froyo) and android 2.3(GingerBread) devices.
I have built application with android 2.3 SDK , and Installed the same application in 2.2(Froyo) and 2.3 (Ginger Bread) devices.
In both the devices application installed successfully and it is working properly.
I want to know if we install the higher version build into lower version devices is there any chances to face problems.
Till now I didn't found any issue with this.
I didn't used the MIN:SDK version field in the Manifest file.
If you want only users from version 2.2 and up to download your app, just make sure your minimum SDK version is 2.2 by putting this line in your AndroidManifest.xml:
<uses-sdk android:minSdkVersion="8" />
If you want an upper bound limit as well, you can add:
android:maxSdkVersion="10"
So users with Android SDK version 2.2 up to 2.3.3 will be able to install your app.
Regarding problems: If you're using a specific SDK API then just make sure to add an if clause around it to make sure you're on the right version. The best thing to do is change the target to 2.2 just to see if you have any compilation errors... Then you'd know what to change.
Then just fix the problems, change back to 2.3 and build.
If you don't specify the minimum sdk attribute in the manifest file users with 2.2 won't see your application on the market. It specifies that your application supports 2.2 so that users can see the app on the market.
Make sure any functionality that you use from 2.3 has an alternative functionality so that 2.2 users have the ability to actually use your application.
yes , u can find problem ,
try to install that app on android 1.6
it's about API version , there will be some APIs in your app doesn't supported in a lower API version

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