[Android] ANDROID_ID

* Definition
- A 64-bit number (as a hex string) that is randomly generated on the device's first boot and should remain constant for the lifetime of the device. (The value may change if a factory reset is performed on the device.)
- 第一次啟動 Android 設備時隨機生成的64位數(以十六進制字符串表示), "應在"保持設備一生不變的. (當設備執行重置出廠值時, 該值可能改變.)

* from level 3

* How to get?
- Settings.Secure.getString(getContentResolver(), Settings.Secure.ANDROID_ID);
- but you will get "null" on emulator.

* Is it unique for each Device?


Update on 20111106

• 透過設定中的選項恢復原廠設定後，ANDROID_ID 仍是相同。
• 若是更新系統，是否仍會相同?
• 重新刷ROM的話，是否仍會相同?

* Reference
- Settings.Secure | Android Developers
- 獲取 Android 設備的 ID，Settings.Secure.ANDROID_ID