1 ## 3.6\. API Namespaces 2 3 Android follows the package and class namespace conventions defined by the Java 4 programming language. To ensure compatibility with third-party applications, 5 device implementers MUST NOT make any prohibited modifications (see below) to 6 these package namespaces: 7 8 * `java.*` 9 * `javax.*` 10 * `sun.*` 11 * `android.*` 12 * `com.android.*` 13 14 That is, they: 15 16 * [C-0-1] MUST NOT modify the publicly exposed APIs on the Android platform 17 by changing any method or class signatures, or by removing classes or class 18 fields. 19 * [C-0-2] MUST NOT add any publicly exposed elements (such as classes or 20 interfaces, or fields or methods to existing classes or interfaces) or Test 21 or System APIs to the APIs in the above namespaces. A publicly exposed 22 element is any construct that is not decorated with the @hide marker as 23 used in the upstream Android source code. 24 25 Device implementers MAY modify the underlying implementation of the APIs, but 26 such modifications: 27 28 * [C-0-3] MUST NOT impact the stated behavior and Java-language signature of 29 any publicly exposed APIs. 30 * [C-0-4] MUST NOT be advertised or otherwise exposed to developers. 31 32 However, device implementers MAY add custom APIs outside the standard Android 33 namespace, but the custom APIs: 34 35 * [C-0-5] MUST NOT be in a namespace owned by or referring to another 36 organization. For instance, device implementers MUST NOT add APIs to the 37 `com.google.*` or similar namespace: only Google may do so. Similarly, 38 Google MUST NOT add APIs to other companies' namespaces. 39 * [C-0-6] MUST be packaged in an Android shared library so that only apps 40 that explicitly use them (via the <uses-library> mechanism) are 41 affected by the increased memory usage of such APIs. 42 43 If a device implementer proposes to improve one of the package namespaces above 44 (such as by adding useful new functionality to an existing API, or adding a new 45 API), the implementer SHOULD visit [source.android.com]( 46 http://source.android.com/) and begin the process for contributing changes and 47 code, according to the information on that site. 48 49 Note that the restrictions above correspond to standard conventions for naming 50 APIs in the Java programming language; this section simply aims to reinforce 51 those conventions and make them binding through inclusion in this Compatibility 52 Definition.
