On May 28, 2015, Google announced the Android M Developer Preview for devices including Nexus 6. This records that experience; the images below show the home screen and Easter egg.

Obsolete experimental procedure · Technical review (2026-10-13): Changing system properties to expose this switch is retained only as history for Nexus 6 (shamu) and the 2015 Android M preview. Google’s later announcement identifies the initial preview as MPZ44Q, but this article retained no device build-number output to verify its exact image. Modern multi-window development uses the versioned APIs discussed at the end, without these system modifications.

The Singleton pattern restricts how instances are created and accessed. This article follows eager initialization, double-checked locking, the holder idiom, and enums, explaining their initialization behavior and limits.

Technical review (2026-10-13): These patterns remain applicable. The discussion is checked against the Java 5+ memory model and Java SE 25 specifications. It corrects the loading/initialization distinction, runtime access checks, and the explanation of enum reflection. The code blocks named Singleton are alternatives, not declarations to combine in one source file.