Date: April 2009
API Level: 3
This document provides version notes for the Android 1.5 system image included in the SDK.
The Android 1.5 system delivered in the SDK (as library and system image) is the development counterpart to the Android 1.5 production system image, deployable to Android-powered handsets starting in May 2009. The system is fully compliant and includes no external libraries. This is the first version of the Android SDK that does not include the Maps external library.
The Android 1.5 system delivers an updated version of the framework API. As with previous versions, the Android 1.5 API is assigned an integer identifier — 3 — that is stored in the system itself. This identifier, called the "API Level", allows the system to correctly determine whether an application is compatible with the system, prior to installing the application.
Applications can reference a specific API Level value in their
manifest files, to indicate the minimum version of the Android system
required to run the application. To reference a minimum API Level, applications
can add an android:minSdkVersion attribute in their manifest files.
The value of the attribute is an integer corresponding to an API Level
identifier. Prior to installing an application, the system then checks the value of
android:minSdkVersion and allows the install only
if the referenced integer is less than or equal to the API Level integer stored
in the system itself.
When you migrate your application to the new SDK, you will need to choose
the platform version against which you will compile your application. In
general, you should compile your application against the lowest possible
version of the platform that your application can support. After you determine
the lowest version, you should ensure that your application's manifest file
defines the API Level of the lowest compatible platform version in the
android:minSdkVersion attribute.
After compiling your application, you should make sure to test it on the
platform specified in the application's android:minSdkVersion attribute. To
ensure forward-compatibility, you should also run the application on platforms
using a higher API Level than that used by your application. To run your
application against different platform versions in the emulator, you create an
AVD for each platform version that you want to test. For more information about
AVDs, see Android Virtual
Devices. If you are using a physical device for testing, ensure that you
know the API Level of the Android platform it runs.
If you build an application using the Android 1.5 library and your
application makes use of any APIs introduced in API Level 3, you must set the
android:minSdkVersion attribute in the application's manifest to
"3".
Specifically, you define the android:minSdkVersion
attribute in a <uses-sdk> element as a child of
<manifest> in the manifest file. When set, the
attribute looks like this:
<manifest> ... <uses-sdk android:minSdkVersion="3" /> ... </manifest>
By setting android:minSdkVersion in this way, you ensure that
users will only be able to install your application if their devices are running
a compatible version of the Android platform. In turn, this ensures that your
application will function properly on their devices. This is especially
important if your application uses APIs or system features
introduced in Android 1.5.
If your application uses APIs introduced in Android 1.5 but does not
declare <uses-sdk android:minSdkVersion="3" />, then it will
run properly on Android 1.5 devices but not on Android 1.0
devices. In the latter case, the application will crash at runtime when
it tries to use the Android 1.5 APIs.
Conversely, if your application does not use any new APIs introduced in Android 1.5, the application will in most cases function normally on devices running a later version of the platform. However, if you have published the application, you are strongly encouraged to install and test your application on the Android 1.5 system image included in the SDK. This will ensure a smooth transition for users, as they upgrade their devices to the new version of the Android platform.
Finally, if your application does not use any new APIs introduced since
Android 1.1, you can indicate general Android 1.1 compatibility by
setting the attribute to "2". If your application does not use any
new APIs introduced since Android 1.0, you can remove the attribute or
set it to "1". However,
before publishing your application, you must make sure to compile your
application against the Android library that corresponds to the application's
android:minSdkVeresion value.
The system image includes these built-in applications:
The system image provides a variety of built-in locales. In some cases, region-specific strings are available for the locales. In other cases, a default version of the language is used. The languages that will be available in the Android 1.5 system image are listed below (with language_country/region locale descriptor).
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Localized UI strings match the locales that are displayable in the emulator, accessible through the device Settings application.
For a list of new system features, see the Android 1.5 Platform Highlights document.
Applications can now use a new element in their manifest files, <uses-
configuration> to indicate to the Android system what hardware features
they require in order to function properly. For example, an application might
use the element to specify that it requires a physical keyboard or a particular
navigation device, such as a trackball. Prior to installing the application, the
Android system checks the attributes defined for the
<uses-configuration> element and allows the installation to
continue only if the required hardware is present.
For a detailed view of API changes in this platform (API Level 3), see the API Differences Report.
