【Android】[Problem]-"Waiting for target device to come online".
环境：
win10专业版（创意者），Android studio 2.3.1
问题描述:
安装玩Android studio之后创建一个项目，建立AVD之后，运行程序时一直不能启动AVD，具体描述为：”Waiting for target device to come online”。即“等待目标设备在线”。
问题分析：
分析1：此处参考了Android 中 adb 相关问题一文，出现此问题的原因大多是因为adb的端口被占用（eclipse，模拟器等）。
分析2：也可能有这种问题，博主就是这种问题，参考了 “waiting for target device to come online” in Android Studio 2.3 一文
问题解决：
分析1：命令行（win+r–cmd）定位到android_sdk/platform-tools/目录下,执行”adb kill-server”
分析2：I was also having the same issue 2 days ago when i update my android studio, today I solve my issue when I was playing around with settings then I saw that in my SDK tools setting Android Emulator is uncheck so I simply checked that box and now emulator is working fine.
Try this steps may work for you also:
Go to SDK tools > SDK Tools
Check Android Emulator and click Apply
