尝试改变usb连接模式到midi设备。这对我很管用。

尝试以下解决方案(适用于Windows):

进入sdk工具安装路径，在\sdk\platform-tools文件夹下运行以下命令: 亚洲开发银行设备

如果你的设备列出了它应该显示如下内容:

C:\android\sdk\platform-tools>adb devices
List of devices attached
081e96500591f039        device

如果没有，请遵循以下方法:

Try these commands: adb kill-server adb start-server Make sure your phone has Developer Options in Settings (if not, go to Settings, About phone (or device), click on Android Version multiple times until you see a message). Make sure USB debugging on your phone is enabled (go to Developer Options in Settings and turn it on) Make sure you have Select USB Configuration set to MTP (this is also in Developer Options). Make sure you can see your files in your device in Windows Explorer when you connect via USB. Make sure you have the driver for your device properly installed (most of the time, this happens when you first plug in your USB cable). In Windows, right click on Computer, and go to Device Manager, check if you have Android Device right on the root folder and under it should be Android Composite ADB Interface. If you don't have this, you have to download the Google USB Driver. Get it here:

http://developer.android.com/sdk/win-usb.html

在设备管理器中，找到您的设备(应该有黄色感叹号)，右键单击，并更新驱动程序(打开带有您刚刚下载的驱动程序的文件夹) 如果这不起作用，尝试重新启动Android Studio或重新插入设备。

一些便宜的设备(一些30美元的平板电脑)不提供USB驱动程序来连接设备管理器，所以在这种情况下你就不走运了。

我的设置

Android Studio 3.5.3 macOS 10.14.6 Android 9设备通过Belkin USB集线器连接到Mac。

当从谷歌的Android github repo运行Kotlin示例项目时，没有配置，也没有设备显示在UI中。

解决方案

File > Sync Project with Gradle Files But my internet connection needs a fix, so I had to go to Preferences > System Settings > HTTP Proxy to specify a working proxy. Make sure buildscript{ ext.kotlin_version } runs a more recent version. I had to upgrade it from 1.2.xx to 1.3.xx. Now the project appears to be ready to build (the default emulator Nexus config is now enabled). Rebuild the project for the emulator just to make sure. Then I had to unplug my device from the USB hub and connect it to Mac directly. Now Android Studio sees my device. Plug the device again into the USB hub. Now Android Studio sees my device with the hub, too.

AVD管理器用于模拟器图像。它从不显示硬件。这适用于任何AVD管理器的使用:Eclipse, Android Studio等。

令人惊讶的是，在Debian Linux上对我有效的只有:

adb kill-server

不用再开始了!!

我一关闭服务器，设备就出现在Android Studio中。我发现这一点的唯一原因是我的终端模拟器窗口是透明的。: D

在我的案例中，以下步骤有助于解决这个问题:

1)确保Android SDK管理器中安装了“谷歌USB Driver”软件包

2)从这里下载“ADB驱动安装程序2.0”

3)运行下载的工具，连接智能手机;在我的例子中，它显示驱动程序安装不正确，并建议修复它

在这些步骤之后，我的Android Studio立即识别了设备!MTP和PTP都开始工作了。

三星(Android 4.1.2)和小米MI4W (Android 4.4.4)测试