Android – disappearing emulator ? Restart adb server

While developing for the Android platform has gotten a lot better in the past year, there are still some rough edges.  In particular, emulators sometimes disappear from the list of attached devices (accessed via adb devices from the terminal, or within the Devices tab when in DDMS view in the Eclipse plugin).  When this happens, you cannot interact with it via the terminal or Eclipse.  That’s a pretty big problem.

A screen shot illustrating a running emulator that does not appear in the list of attached devices

An emulator within the devices window

To solve this, you should take the following steps:

# Device is running but not showing up
[497][nicholasdunn: /Users/nicholasdunn]$ adb devices
List of devices attached

# Kill and restart
[498][nicholasdunn: /Users/nicholasdunn]$ adb kill-server
[499][nicholasdunn: /Users/nicholasdunn]$ adb start-server
* daemon not running. starting it now *
* daemon started successfully *

# Device appears, but is listed as offline
[500][nicholasdunn: /Users/nicholasdunn]$ adb devices
List of devices attached
emulator-5554    offline

# One more invocation of adb devices should get it recognized
[501][nicholasdunn: /Users/nicholasdunn]$ adb devices
List of devices attached
emulator-5554    device

If this happens to you frequently (it does to me), you can create an alias within your .bash_profile file (~/.bash_profile):

alias adb-restart='adb kill-server; adb start-server; adb devices; adb devices'

Reload your .bash_profile file:

source ~/.bash_profile

You can then invoke it from the terminal by typing adb-restart.  Sometimes one invocation of adb devices is enough to have the emulator show up as a device; others requires two.  Not sure why that is.  To be safe I’m including two in the script.