Android Failed to install HelloWorld.apk on device (null) Error

编写第一个android程序就出现这个问题。摘抄网上的一个方法：

问：

I am new to Android. When I am running my android application in eclipse I am getting these messages in the console:

[2011-03-08 12:57:35 - HelloWorld] ------------------------------
[2011-03-08 12:57:35 - HelloWorld] Android Launch!
[2011-03-08 12:57:35 - HelloWorld] adb is running normally.
[2011-03-08 12:57:35 - HelloWorld] Performing com.oreilly.helloworld.HelloWorldActivity activity launch
[2011-03-08 12:57:35 - HelloWorld] Automatic Target Mode: Preferred AVD 'MY_AVD' is not available. Launching new emulator.
[2011-03-08 12:57:35 - HelloWorld] Launching a new emulator with Virtual Device 'MY_AVD'
[2011-03-08 12:57:39 - HelloWorld] New emulator found: emulator-5554
[2011-03-08 12:57:39 - HelloWorld] Waiting for HOME ('android.process.acore') to be launched...
[2011-03-08 13:00:14 - HelloWorld] WARNING: Application does not specify an API level requirement!
[2011-03-08 13:00:14 - HelloWorld] Device API version is 11 (Android 3.0)
[2011-03-08 13:00:14 - HelloWorld] HOME is up on device 'emulator-5554'
[2011-03-08 13:00:14 - HelloWorld] Uploading HelloWorld.apk onto device 'emulator-5554'
[2011-03-08 13:00:14 - HelloWorld] Installing HelloWorld.apk...
[2011-03-08 13:02:22 - HelloWorld] Failed to install HelloWorld.apk on device 'emulator-5554!
[2011-03-08 13:02:22 - HelloWorld] (null)
[2011-03-08 13:02:23 - HelloWorld] Launch canceled!

How do I resolve the problems so that my application will launch?

答：

Try changing the ADB connection timeout. I think it defaults that to 5000ms and I changed mine to 10000ms to get rid of that problem. If you are in Eclipse, you can do this by going through Window -> Preferences and then it is in DDMS under Android.（我用这个成功了。）