android:minSdkVersion An integer designating the minimum API Level required for the application to run. The Android system will prevent the user from installing the application if the system's API Level is lower than the value specified in this attribute. You should always declare this attribute. Caution: If you do not declare this attribute, the system assumes a default value of "1", which indicates that your application is compatible with all versions of Android. If your application is not compatible with all versions (for instance, it uses APIs introduced in API Level 3) and you have not declared the proper minSdkVersion, then when installed on a system with an API Level less than 3, the application will crash during runtime when attempting to access the unavailable APIs. For this reason, be certain to declare the appropriate API Level in the minSdkVersion attribute.
android:targetSdkVersion An integer designating the API Level that the application targets. If not set, the default value equals that given to minSdkVersion. This attribute informs the system that you have tested against the target version and the system should not enable any compatibility behaviors to maintain your app's forward-compatibility with the target version. The application is still able to run on older versions (down to minSdkVersion).
As Android evolves with each new version, some behaviors and even appearances might change. However, if the API level of the platform is higher than the version declared by your app's targetSdkVersion, the system may enable compatibility behaviors to ensure that your app continues to work the way you expect. You can disable such compatibility behaviors by specifying targetSdkVersion to match the API level of the platform on which it's running. For example, setting this value to "11" or higher allows the system to apply a new default theme (Holo) to your app when running on Android 3.0 or higher and also disables screen compatibility mode when running on larger screens (because support for API level 11 implicitly supports larger screens).
There are many compatibility behaviors that the system may enable based on the value you set for this attribute. Several of these behaviors are described by the corresponding platform versions in the Build.VERSION_CODES reference.
To maintain your application along with each Android release, you should increase the value of this attribute to match the latest API level, then thoroughly test your application on the corresponding platform version.
Introduced in: API Level 4
android:maxSdkVersion An integer designating the maximum API Level on which the application is designed to run. In Android 1.5, 1.6, 2.0, and 2.0.1, the system checks the value of this attribute when installing an application and when re-validating the application after a system update. In either case, if the application's maxSdkVersion attribute is lower than the API Level used by the system itself, then the system will not allow the application to be installed. In the case of re-validation after system update, this effectively removes your application from the device.
To illustrate how this attribute can affect your application after system updates, consider the following example:
An application declaring maxSdkVersion="5" in its manifest is published on Google Play. A user whose device is running Android 1.6 (API Level 4) downloads and installs the app. After a few weeks, the user receives an over-the-air system update to Android 2.0 (API Level 5). After the update is installed, the system checks the application's maxSdkVersion and successfully re-validates it. The application functions as normal. However, some time later, the device receives another system update, this time to Android 2.0.1 (API Level 6). After the update, the system can no longer re-validate the application because the system's own API Level (6) is now higher than the maximum supported by the application (5). The system prevents the application from being visible to the user, in effect removing it from the device.
Warning: Declaring this attribute is not recommended. First, there is no need to set the attribute as means of blocking deployment of your application onto new versions of the Android platform as they are released. By design, new versions of the platform are fully backward-compatible. Your application should work properly on new versions, provided it uses only standard APIs and follows development best practices. Second, note that in some cases, declaring the attribute can result in your application being removed from users' devices after a system update to a higher API Level. Most devices on which your application is likely to be installed will receive periodic system updates over the air, so you should consider their effect on your application before setting this attribute.
Introduced in: API Level 4
Future versions of Android (beyond Android 2.0.1) will no longer check or enforce the maxSdkVersion attribute during installation or re-validation. Google Play will continue to use the attribute as a filter, however, when presenting users with applications available for download.
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