Develop Reference

Setting up a HUDL as a debugging device?

I'm using an ASUS X75VC laptop running Windows 8.1 and am trying to enable application debugging on my Tesco HUDL running Android 4.2.2. I have been trying and failing different techniques for the last few hours so decided I will post to see if anyone else can pinpoint the problem.
I've checked the following;
My Android project is set to use 4.2.2 as the API.
My HUDL has developer mode turned on and allows the use of non-market applications.
When plugged in my HUDL displays the messages;
"Connected as a media device".
"USB Debugging connected".
However, using the command "adb.exe devices" does not list my device, and attempting to run the project while manually selecting a device doesn't display my device in the list.
I have searched for drivers on ASUS website however am not completely sure what I'm looking for as the results I had been shown were all to do with graphics card updates and such, no USB.
If anyone can help me it will be much appreciated.
Many thanks.

I got my hudl to work as a debug device on android studio with windows 10.
First you have to enable developer options (use google). Then connect as a media device.
It the appears as a connectable device wen yo run the app in android studio. You have to enable debugging on your hudl notifications.

Go to Control Panel > Device Manager.
Check that there is an exclamation mark next to Other Devices > ADB Interface, meaning that the driver is not installed.
For the ADB Interface, select Update Driver > Browse my computer for driver software > Let me pick from a list of... > Have Disk... > Enter the path to your Android SDK USB driver folder (ie. C:\Program Files (x86)\Android\sdk\extras\google\usb_driver).
Ignore the warning and complete the installation.

I managed to get my hudl 2 to work with a good bit of messing about. some of these steps may not be necessary but in the end i got the hudl debugging
Connect the Hudl via usb
On the Hudl change its connection mode from media device to camera
Download and install the following stuff https://software.intel.com/en-us/android/articles/intel-usb-driver-for-android-devices
Open the device manager and look in Other Devices
Right Click the ADB device and update driver
Select Browse computer for driver
Click let me pick from a list of devices
Select the Samsung device driver
Remove and reconnect the hudl via usb. the hudl should then have a popup asking for you to accept connections via the pc. allow it and your hudl should then be available for debugging
I was debugging through Xamarin studio at the time

LG G2 vs980 not recognized by ADB devices command (Win7 on virtualbox)

I have been developing android mobile apps via eclipse in school for some time now, deploying the apps to virtual devices. However, I now want to deploy them to my LG G2 android device for testing and speed purposes. I know there are posts about other devices not working, but the solutions are to no avail for me.
I am on virtualbox running windows 7. I have the necessary vb extensions installed and vb DOES detect my LG G2 (asks to view folders..etc), however eclipse/adb on my vb cannot find it still.
I have put what I thought is the proper device vendor id (1004, 0232) in the adb_usb.ini file since some others found that to help get their device detected.
I have done the commands adb kill-server & start-server many times. I have restarted the phone and vb also. I have also tried all of the phones connection types (internet/ethernet, MTP)
Some help would be awesome,
Thanks fellas

When you plug the phone in, you are given options for the "USB connection method".
You must select Internet connection or Send Images (PTP) from the list in order to use USB Debugging tools.
For selecting Internet Connection, the other options sometimes include Charge phone, Media sync, and Camera.
For selecting Send Images (PTP), the other options sometimes include Charge Phone and Media Device (MTP).

Here are may be several solutions:
1) When your device connected open Device manager(default windows tool) and found Unknown device or some not properly recognized device and try to setup driver manually.
2) Enable USB debugging option in phone settings:
go to Setting->About Phone and tap several times on Build Number,
then go back (Settings->Developer -> Options) and turn it on
3) Try to update your USB driver/adb via Android Manager launched from Eclipse.

When I upgraded my LG g2 from Android 4.4 to 5.0.2, usb debugging stopped working.
I didnt have an "Internet" option for USB connection method.
Through lots of trial, error, searching, experimenting, the I found that enabling "USB tethering" (in Settings -> Tethering & Networks -> USB Tethering) did the trick. Once I enabled USB tethering, I could download debugging programs via adb/AndroidStudio. Before USB tethering enabled, adb could not recognize my 5.0.2 device.

How to Setup ADB on Windows
Download the Android SDK package for Windows [android-sdk_r21.1-windows.zip]
Extract the zip files to your C:\ drive. Now you have a folder android-sdk-linux
Double click on SDK Manager to initiate the SDK manager. You shall perceive the following window.
Make sure everything is un-ticked. Now select Android SDK Platform-tools and install it.
During the next window, you will be prompted. Accept the license and click on Install.
When the installation is complete, close the window.
The SDK manager has now download the platform-tools successfully, which certainly includes our prior ADB.
The next step is to define the path where ADB is present.
Go to C:\android-sdk-windows\platform-tools and take note of this path.
Go to desktop, right click on Computer and select Properties.
On the left pane, click on Advanced System Settings and a new window shall open.
Select Environment Variables under Advanced tab.
Select Path variable and click edit.
Now add the path we noted in step #9 to the variable value and hit OK.
Confirm and apply all the changes.
To confirm that ADB has been configured properly, open CMD window and type in:
adb
You now have ADB successfully installed and configured on your Windows machine

adb doesn't show nexus 5 device

Android Studio 0.3.6
Fedora 18 3.11.7-100.fc18.x86_64
Nexus 5 Kitkat
Hello,
I have been using my Samsung Galaxy Tab 3 7.0 running Android 4.1.2 everything works fine with adb.
However, I have just bought a new Nexus 5 device, and when I do the following command adb devices it doesn't show my Nexus 5.
Under Android SDK Manager | Extras | Google USB Driver | status "Not compatiable with Linux"
Because I am running Fedora 18 if I need drivers what drivers for the USB do I need?
Because the Samsung works fine and I can deploy and run my apps, I think my setup is correct. So I am wondering if there is something wrong with my Nexus 5.
I have tried the following:
adb kill-server
adb start-server
Setting the Nexus 5 Camera PTP and media device MTP didn't work.
Many thanks for any suggestions,

I had a similar problem with my Nexus 4(Android version 4.4.2), it wasn't listed in adb devices.
Make sure USB debugging is enabled from device, and do the following on your PC:
Update Android SDK (Google USB Driver)
From PC Control Panel, System -> Device manager -> Right click Nexus 4 -> Update driver.
Set android-sdk-folder\extras\google\usb_driver as path to search, include subfolders checked.
If windows tells you that the driver is up to date, just uninstall the driver (right click on nexu4 -> uninstall driver) and start from step 2 again.
After that, open a cmd and type adb kill-server and then a adb devices, now it will include your device.
https://developer.android.com/studio/run/oem-usb.html

Follow these steps,
Enable Developer options in your device. To enable the developer mode, Settings->About phone, tap Build number option 7 times continuously
Go to Settings-> Developer options and Turn on USB debugging
Make sure you reconnected the device via USB and grant permission on the dialog that appears.
From the above steps it didn't work try this step, Go to Settings->Security and turn on Unknown Sources

What you need to do is this:
Settings | About Phone
Scroll to the bottom to build number.
Tap on build number about 7 times. Each time you will get a popup message saying you are x steps away from being a developer
When you get to the final step you will get a message saying now you are a developer
Go back into settings and you will see a new setting Developer options there you will see a lot of options for developers. Enable USB debugging
Re-connect you phone to the usb, and you should see you device under adb devices.
I hope this answer helps someone else.

This simple steps worked for me, I debug on my Nexus 5 and 5X devices on Windows 8.1.
The steps to follow are these:
1) Enable from Developers Options the Debug USB Mode
2) Unplug the device from the computer
3.1) Go to Settings → Storage, in the ActionBar, click the option menu and choose USB computer connection.
3.2) If you didn't find the 3.1) option then go to Settings → Developers Options → Select USB Configuration.
4) Select Camera (PTP) connection.
5) Plug the device and you should have a popup on the device allowing you to accept the computer's incoming connection, or something like that.
6) If it doesn't work try to toggle the Debug USB Mode in the Developers Options
Finally, you should see it now in the DDMS and voilà.

My windows solution:
Go here and download and unzip to an easy location:
http://developer.android.com/sdk/win-usb.html#top
Right click 'My Computer' or 'Computer'
Select properties
Select Device manager
Look for your device. It should have a yellow mark above it.
Click 'update driver software'.
select browse my computer for driver software.
select the usb_driver folder you saved earlier.
install it
and wala. magic.

For those who are still frustrated, if you are using the experimental ART runtime, try switching back to dalvik (in developer options on device)

Here is simple solution for Windows 7 and Nexus 5 on Android 5.
Download the Nexus 5 Drivers from http://androidhost.org/jelry
Extract the zip contents and place all files in a single folder on your desktop.
Connect your device to your computer.
Launch the Device Manager on your PC.
Now you should see the Nexus 5 listed in the hardware list.
Right-click the ‘Nexus 5′ line and then click on Update Driver Software.
Next, click the ‘browse my computer’ option.
In the new window click on ‘Browse…’ button.
Go to folder unzipped at step 2. Select the folder where you extract the USB Drivers. Click Next. – make sure to tick the subfolder box too.
Now, the Windows installer will search for Nexus 5 drivers, click Install when asked for permission.
Wait for the process to complete and then check the Device Manager list to confirm that the installation was successful.
Original: http://www.android.gs/download-and-install-google-nexus-5-usb-drivers-adb-fastboot/
Note: do not forget to enable USB debugging on your device :)

Something nobody has mentioned yet:
Some cables do NOT support data. I was sitting here wondering why my Nexus 5 was refusing to show up on OSX. It turned out I was using a cable that didn't support data.
I swapped to a different cable which did support it, and suddenly I was able to use USB debugging.

If anyone is trying to connect Nexus 5 to a formatted Windows XP then follow these steps:
Download and install media transfer protocol porting kit:
MTP porting kit
Download and install WMFDistributable-11 for XP:
WMFDist-11 XP
Download and install LG United Mobile Driver v3.10.1:
stackoverflow is not allowing to share more than 2 links, please google this.
Connect your device.
Go to Device Management
Right click on Nexus 5 and click Update Driver
Select Yes this time only
Select Install Software Automatically
Wait for sometime.. and enjoy transferring files

ADB and driver versions matter. The newer the device, the lower the chances of an older version ADB to work correctly.
Apps using their own ADB copy need to be updated or at least have their ADB updated manually.
When installing Helium / Carbon for instance, it uses an old / incomplete ADB. Newer devices might not link to the ADB server for this very reason.
What I'm writing here should work for any future devices on Windows and possibly *nix OSes.
First the systems must be prepared.
on Android:
activate developer mode, either from an app (like Helium, when prompted) or by accessing the about phone section, taping build number until the developer mode unlocks
in developer settings enable USB debugging
in security settings allow unknown sources
(when connected with USB cable) set USB connectivity to PTP mode (camera device, if so labeled)
in Windows:
uninstall older USB driver (with file removal) if there is one, but only when the device is connected and in developer mode, otherwise
that particular device won't be listed
install latest USB driver after the device has been plugged in and developer mode is active, the device will be listed as unknown or other in Device Manager; the drivers can be downloaded separately from Google Android support site, these are the same as vendor drivers, with only fewer ID's in inf file making the driver not being recognized for all Android devices
if the driver does not recognise the device, no problem, install it generically: Manual Install > Show All Devices > Have Disk > pick inf location of the Android USB driver and from the list select Android ADB Interface; there's not need to edit the inf by adding hardware ids, the end result is the same
each of the modes, PTP and MTP will have their own driver entry, so if the device asks for MTP, the same driver installation procedure must be followed, again
Once these steps are/were previously done correctly, adb must be tested.
If Android SDK was installed previously, open a command prompt where adb.exe is
and test the listing of the device.
adb start-server
IMPORTANT NOTE: This command will prompt the device to allow the communication between the computer it's been linked to on the first run. The prompt will also list an RSA key specific to the PC in question. Without this prompt on start-server, ADB will NOT work! Nor will any application relying on ADB.
adb devices
Must list the device(s). If the list is empty, and most likely the RSA prompt did not occur, then no communication will work. If the list is empty the current ADB (and SDK) must be updated or installed fresh (in the case of apps bringing in their own ADB runtime, like Helium / Carbon).
In the case of applications that do bring their own ADB, if the version is old, and these apps insist in using it instead of the SDK one, these files need to be replaced with the latest ones from Android SDK. Plain and simple copy & paste.
As for Android SDK, the only required packages to be installed are SDK Tools and Platform-tools. There, ADB.exe will need some support libraries, on Windows these files are AdbWinApi.dll and AdbWinUsbApi.dll. After all is done, the SDK can be uninstalled from SDK Manager while being able to retain the ADB tool if this is the only runtime used, depending on the case in question.

After doing all steps like enable debug, ... I had to put a sim card and reboot the phone

Solution for Windows 7 and Nexus 5 (should be applicable for any Nexus device):
I figured out that my system was installing the Nexus 5 default driver for windows automatically the moment I was connecting my Nexus 5 to my system through USB. So uninstalling the default driver was in vain and it gets installed automatically anyways.Moreover if you uninstall the default driver, you won't be able to locate Nexus 5 under Devices in Computer Management. So here is what i did and worked for me!
Computer-->right Click-->Manage-->Device Manager-->Portable Device-->Nexus 5-->Update Driver Software
Choose 'Browse my computer for driver software'
1.Make sure to give this location: %APPDATA%\Local\Android\sdk\extras\google\usb_driver
Click Next and you are done.

I have suffered the same issue and was able to solve it by simply changing on my Android device (Nexus 5X) in Developer options > Select USB Configuration to RNDIS (USB Ethernet)

For those trying to connect their android phone in adb with no luck and have tried every USB configuration (MTP, PTP, RNDIS). It is worthing noting that in my case with my Nexus 5X on Windows 7 I successfully connected the phone to adb only by choosing the Charging USB Configuration. With any other configuration (MTP, PTP, ...) it doesn't work.
USB Driver: Google USB Driver v11
ADB Version: Android Debug Bridge version 1.0.39

Madx's answer is a strong hint. Now I can make MTP work for my Ubuntu 20 and Nexus 5X (Android 8) device. MTP is an easy solution in Windows for smartphone users. However, to me and many Ubuntu/Linux users, current Ubuntu/Linux MTP tools "LOOK" messy and unstable for Android devices, e.g. No folder is shown for android phone in Nautilus.
Delving deeper I find it might be a security enhancement done by GOOGLE in the Android device/phone side. Direct internal data access remains a privilege for the developers. And one needs to set/reset MTP as a developer for Android device in order to make Ubuntu MTP tools work. There is nothing wrong with Ubuntu/Linux MTP tools.
The steps for MTP data access are an extension to Madx's answer:
(For Android device) Enable from Developers Options the Debug USB Mode.
Unplug the device from the computer.
3.1) Go to Settings → Storage, in the ActionBar, click the option menu and choose USB computer connection.
3.2) If you didn't find the 3.1) option then go to Settings → Developers Options → Select USB Configuration.
4.1) Select MTP connection.
4.2) Select Camera (PTP) connection.
4.3) Select MTP connection again. (This refreshs GOOGLE MTP protocol stack, I guess)
Plug the device and you should have a popup on the device allowing you to accept the computer's incoming connection, or something like that.
If it doesn't work try to toggle the Debug USB Mode in the Developers Options
And now file folders are shown up for N5X device in Nautilus.
Are these too much? There might be a bug in Android MTP implementation, and 4.2) & 4.3) are steps to WAKE Up Android MTP stack:-)
As a kind reminder, Windows and FTP are the last resorts for MTP.

Try executing :
sudo ./adb kill-server
sudo ./adb start-server
sudo ./adb devices

In my case:
The phone was connected as a media device.
Clicked on that message and got a menu. "USB computer connection"
In that menu chose to connect it as a camera (for devices that do not support MTP)
And then it worked.

Oh boy, I spent 3 hours for this simple thing and tried combination of above instructions.If it doesnt work for you, just try several combinations of above instructions and it will. I am on windows 7 and nexus 5. Issue I had was when I try to install driver from the google usb folder, windows 7 fails to install. Here are my steps:
-first uninstall all nexus drivers on windows 7. connect with USB cable, go to device manager and uninstall the driver; unplug the cable and repeat until no drivers are found and nexus shows up under "other devices" in device manager. I also configured nexus device as camera (PTP)
-follow #Dharani Kumar instructions. They make appropriate configuration changes for nexus device
-follow #Harshit Rathi instructions. They will ensure eclipse can show the device when windows detects the device
-unplug and replug the USB cable after a minute. Now you should see a pop up on nexus device. click it so that windows 7 will allow installing the driver from your local system. if you dont see this, restart your device or pc
-follow #Rick's instructions.you can download USB driver as listed by #jimbob
If you still have a problem, re read this entire thread and go from there (I spent hours on other web sites; those bits and pieces didnt help)

Go here and download and unzip to an easy location:
http://developer.android.com/sdk/win-usb.html#top
Download and install

I had the same problem, USB debugging enabled, device showing up in windows but I never got the question about RSA fingerprint when I connected my Nexus (6) device, nor did it show up in the Android Device Manager.
BUT
In the windows device manager I did have an entry saying it was an android device and Composite ADB interface etc. Still didn't work.
When I tried the previous tips about manually updating the drivers, Windows 8.1 just responded that "Windows has determined that the driver software for your device is up to date" this was not true. Looking at the driver details I saw that the driver was published by "ClockworkMod". I realized this must be because I had installed the Helium app sometime last year. So I uninstalled that, still had the same problem. Checked again, this time it was indeed google drivers, but version 7 published in 2012 (and not version 11 published 2014). I uninstalled these AS WELL and then tried the trick of reinstalling the driver from the SDK located in:
%localappdata%\Android\sdk\extras\google\usb_driver
Now when I replugged my device it finally works and can be debugged with Android Studio.
Indeed a driver problem.

Answer by Rick and MadX is the right way to do the steps (Thumbs Up for the answer)
In my case I am using
Akcess USB Type C Data Sync Cable For Nexus 5x, 5P - White
As Nexus 5x do not supply type C to usb cable I purchased it from some vendor.
Having the same issue. What I am doing stupidly is:-
I am connecting the cable in wrong way. After I reconnect it from upside down its working for me.
I might think that some of the Cables do not support debuggable. But its in my case.
This(Image) is my case the Type C should be as USB side symbol. A stupid solution, but work for me

ADB No Devices Found

I am attempting to install an Android app on my brand new Nexus 10. I have a .apk file. I have downloaded the Android SDK, installed "Android SDK Tools", "Android SDK Platform-tools", and Google USB Driver. I have checked the setting on my Nexus 10 for "Unknown Sources".
When I run "adb devices" from the command terminal, it doesn't list any devices. I attempted to follow this recommendation, because it was identical to a suggestion I had previously found here on Stack Overflow. After following those steps, "adb devices" still returns an empty list and to make it worse, when I connect my Nexus 10 to my PC, Windows doesn't show any folders within the device.
I have undone the steps in that link, along with everything else I have done so far, as well as uninstalling my Nexus 10 from Device Manager and reinstalling it, but I am still not seeing any folders in the device.
Is there anything I am missing to get my device to show up in ADB devices?
What can I do to get Windows to see the folders within the device?

Windows 8 wouldn't recognize my Nexus 10 device. Fixed by Setting the transfer mode to Camera (PTP) through the settings dialogue on the device.
Settings > Storage > Menu > USB Computer connection to "Camera (PTP)"

For Windows 8 users:
After trying every solution given here, with no success, I found this:
Go to Device Manager
Browse my computer for drivers -> Let me pick from a list of device drivers on my computer
Choose Android Device and then Android ADB Interface.
Now I have my devices listed at adb devices.

This situation seems to arise with some ADB drivers. I have encountered the same thing with a couple of Google devices and installing the Universal ADB windows driver has fixed it for me every time.

Use another cable.
Just found out that one of my regular charging cables had Vcc, Gnd pairs, but no Data+, Data-.
https://en.wikipedia.org/wiki/USB#Pinouts

Make sure to Enable USB debugging in Settings -> Developer options
Also, run "adb devices" after getting into the platform tools folder in the Android SDK (unless you have that folder on your system path already), otherwise the command won't be found.

The device may not be visible for debugging if it is in MTP mode. Some devices only work in PTP mode (or even in "charging only" mode).
This can be changed in Settings > Developer Options > Networking > Default USB configuration > PTP.
Also, you'll get a notification on your android device asking you for confirmation about USB configuration setting change and to allow it.
Note: You can turn on developer options by following the link below:
enable developer options

I have found a solution (for Windows 7):
Connect your Nexus 10 to PC
Go to Windows Device Manager
RClick on ADB Interface -> properties
Details -> Hardware Ids.
You will see two records like these:
USB\VID_18D1&PID_4EE2
USB\VID_18D1&PID_4EE2&MI_01
5 Open the android_winusb.inf file (I have it in "C:\Users\<username>\AppData\Local\Android\android-sdk\extras\google\usb_driver" directory)
6 Create such records in [Google.NTx86] and [Google.NTamd64] sections using Hardware Ids from properties of ADB interface:
;Google Nexus 10
%SingleAdbInterface% = USB_Install, USB\VID_18D1&PID_4EE2
%CompositeAdbInterface% = USB_Install, USB\VID_18D1&PID_4EE2&MI_01
7 Save the file, and update driver for ADB Interface with showing the path to "C:\Users\\AppData\Local\Android\android-sdk\extras\google\usb_driver" directory

Sometimes ADB loses connection to the device, and needs to be reset. If you have everything else working (ie USB driver installed, Developer settings enabled on the device), and still can't see your device, you need to reset the ADB process.
This is available in the DDMS Perspective (from within Eclipse), Devices tab (the triangle on the far right includes a menu item to perform the reset).
Otherwise from the command line, you can reset it with the following 2 commands:
adb kill-server
then
adb start-server

Enable Developer options in your device. To enable the developer mode, setting->About phone, tap Build number option 8 times continuously
Go to Settings-> Developer options and Turn on USB debugging
From the above steps it didn't work try this step, Go to Settings->Security and turn on Allow Unknown Resources

You have to download the drivers from the SDK manager (extras → Google USB Driver)
Then you have to install the USB driver in Windows (it works for me in Windows 8.1):
(Copy and paste from http://developer.android.com/tools/extras/oem-usb.html#InstallingDriver:)
Connect your Android-powered device to your computer's USB port.
Right-click on "Computer" from your desktop or Windows Explorer, and select "Manage".
Select "Devices" in the left pane.
Locate and expand "Other device" in the right pane.
Right-click the device name (such as Nexus S) and select "Update Driver Software." This will launch the "Hardware Update Wizard".
Select "Browse my computer for driver software" and click "Next."
Click "Browse" and locate the USB driver folder. (The Google USB Driver is located in <sdk>\extras\google\usb_driver\.)
Click "Next" to install the driver.

After downloading the Google drivers via Android SDK Manager (available via Eclipse, Intellij or Android Studio), I had to update the driver in Computer Management > Device Manager > Other Devices > ADB - right clicking and clicking on update driver and browsing for updated driver finally did the trick.
BTW, a total nightmare for me as well. I continue to be bewildered that setting up a dev environment should be the most difficult task imaginable, with each new inexplicable failure leading to another one. Jeesh! Good luck.

On my Windows 8.1 64bit (Nexus 5 did not show up), only manually installing the USB driver fixed it:
http://developer.android.com/sdk/win-usb.html
The "Google USB Driver" in "Android SDK Manager" was installed already.

I still get this once in a while and it usually works if I unplug it and plug it back in a different port. I'm on Linux but had the same thing happen on Windows before.

Installing Samsung Kies and using their tool to reinstall device drivers, is what finally worked for me with my Galaxy S3 and Tab S 8.4

Normally SDB will download the driver in the **android-sdk-windows\extras\google\usb_driver** path
Here are the steps that worked for me:
Enable USB debugging.
Do to device manager, right click on ADB device and click update driver software.
Select "Browse my computer for Driver Software"
Select "Let me pick from list of Device drivers on my computer"
Click on "Have Disk" option.
Select the driver path **android-sdk-windows\extras\google\usb_driver** (path of sdk)
7.Select 1st driver out of list of drivers shown.
And hopefully, it will work.

Edit: I recommend you DO NOT run ADB under VirtualBox if you are using a Windows Host. Somehow I got VirtualBox to lock the device drivers on the host, eventually making it so that the ADB wouldn't work on the client nor the host for any device I plugged in. To fix, I removed VirtualBox extensions on the host and ran http://www.nirsoft.net/utils/usb_devices_view.html to delete the incorrect drivers. I could not get the correct drivers to load while VirtualBox extensions were installed, and this problem was a complete bastard to diagnose and fix.
Edit 2: Also the following is probably out of date, now that Google have released an integrated ADB extension for Chrome.
What an installation nightmare... Here are the steps I needed to get my Nexus 10 recognised on an XP virtual machine running under VirtualBox:
If you get asked to install Nexus 10 drivers, make sure to untick "don't ask again" (you WANT to be asked again!).
Plug in the Nexus 10 USB connection
Turn on debugging in the Nexus 10 settings Developer menu (tap "About Tablet" 7 times to get that menu).
In your virtual machine settings (host), add the samsung Nexus 10 device to the USB Device Filters (important - selecting it from the devices menu didn't seem to work).
In guest install java jre (if you don't have java installed). In Control Panel, change Java settings so that java doesn't run in the browser (to help prevent security issues).
In guest get the adk zip file and put it somewhere permanent. I needed to delete the .android config directory from the user directory because I moved the directory.
Run the SDK Manager.exe - if it doesn't work, try running sdk\tools\android.bat which seems to give better error reporting.
From SDK Manager install the Google USB driver package.
Unplug the Nexus 10 and plug it in again, and install the Google USB driver package.
Restart the guest.
running c:>[...]\sdk\platformtools> adb devices finally shows me the device...

For the Blu Studio 5.5s ADB drivers, you have to go through this hoop. I am certain it is the same with all Blu phones or maybe for all non-Google mfg phones, I am not sure. First of all if you connect the Blu device with USB cable and USB Debuggin off, you will see that Windows 7 loads a generic driver for you to copy on/off files to the phone and SD storage. This will appear when the USB cable is first plugged in and appears as a device icon under Control Panel, Device Manager, Portable Devices, BLU STUDIO 5.5 S (or the device you are working with). Do not bother getting the hardware ID yet - just observe that this happens (which indicates you are good so far and don't have a bad cable or something).
Go to the phone and switch on USB Debugging in the Developer section of your phone. Notice that an additional item appears as an undefined device now in the device manager list, it will have the yellow exclamation mark and it may have the same name of the phone listed as you saw under Portable Devices. Ignore this item for the moment. Now, without doing anything to the phone (it should be already in USB debug mode) go back to the Portable Devices in Device Manager and right-click the BLU STUDIO 5.5 S or whatever phone you are working with that is listed there without the exclamation mark (listed under Portable Devices). Right click on the icon under Portable Devices, in this example the name that appears is BLU STUDIO 5.5 S. On that icon select Properties, Details, and under the pull down, select Hardware IDs and copy down what you see.
For BLU STUDIO 5.5 S I get:
USB\VID_0BB4&PID_0C02&REV_0216&MI_00
USB\VID_0BB4&PID_0C02&MI_00
(Note if you do this out of turn, the HW ID will be different with the phone USB debugging turned off. You want to copy the value that it changes to when the USB debugging is ON)
Now do as the instructions say above, of course customizing the lines you add the the INF file with those relating to your own phone, not the Nexus 10. Here is what to customize; when you downloaded the SDK you should have a file structure expanded from the ZIP such as this:
\adt-bundle-windows-x86_64-20140321\sdk\extras\google\usb_driver
Find the file named: android_winusb.inf in the usb_driver folder
Make a copy of it and name it anything, such as myname.inf
Edit the myname.inf and add the lines as instructed above only modified for your particular phone. For example, for the BLU STUDIO 5.5 S, I added the following 2 lines as instructed in the 2 locations as instructed.
;BLU STUDIO 5.5 S
%SingleAdbInterface% = USB_Install, USB\VID_0BB4&PID_0C02&REV_0216&MI_00
%CompositeAdbInterface% = USB_Install, USB\VID_0BB4&PID_0C02&MI_00
Note that you add these lines to both the 32 and 64 bit sections, matching how the example in the tutorial reads.
Now go back up to the unknown device that appeared in Device Manager when you switched on device USB debugging and right click on this item (has yellow exclamation mark), right click on it and then select Update Driver Software, and then Browse My Computer, Let Me Pick, click on the Have Disk button and browse to find the myname.inf. Continue to agree to all the prompts warning you it might not be the right driver. As the final step, Windows should have identified the device as Android ADB Interface and once that is done, you should be able to go back, open your CMD window and run the command "adb devices" as instructed in this tutorial and now you should see that the phone is now discovered and communicating.
Now you can go have fun with the adb command.

At first Thanks #rmsyk's post.
For my issue and after long time suffering with Meizu C9 Pro witch require just android ADB drivers (no special drivers) referring to manufacturer and it solved in my Windows 7 PC by the bellow steps.
Make Sure to
Install latest version of ADB & Fastboot with the needed drivers.
Enable Developer options & USB Debugging.
Enable Media File Transfer (MTP Mode).
Manually replace C:\Users\USERNAME\.android with the folder included here ,Then kill process 'adb.exe' if found from Windows Task Manager and use adb devices and finally my device listed successfully and just confirm the PC as trusted.
Notes:
Android Studio was uninstalled in earlier time and also i tried to reinstall but was not a solution at all.
Tried adb kill-server & adb start-server but was not a solution too.

As well as the usual settings (enable USB debugging) I also had to select Enable OEM unlock in the Developer options.
This supposedly makes the device less secure, but it's your device and you know what you want to do.
Once checked the device behaved as expected and appears in the adb devices list.
You can always reverse all these settings once you're finished.

Confirm you have the correct platform SDK tools
For Windows 10, had to manually download the latest platform SDK tools from Android as the version supplied through Visual Studio 2017 EMDK for Xamarin was not sufficient. Everything else except adb.exe devices worked.
https://developer.android.com/studio/releases/platform-tools
After the platform tools were manually downloaded, device showed up regardless of USB configuration (charging, MTP, etc.)
Installing an emulator device at this stage is also helpful to see whether the problem is with adb or your physical device.
List of devices attached
12345D1234 device
emulator-5554 device

There could be two reasons why adb devices command is not working for you. Either your phones USB drivers are not installed properly or you have not enabled USB debugging mode.
I created a tool that makes installing USB drivers a one click thing.
Just connect your phone in USB debugging mode to PC.
Run my tool
It will detect and install drivers specific to your phone and also install the latest ADB & Fastboot binaries with it.
The tool is available at my GitHub Repo

It's so easy, just turn off your Android device, and then hold down both "Volume Down" key and "Power" at the same time. Wait a few seconds till it start in recovery mode, done.
Now type adb devices, and you'll see your device.

I had the same problem with my Windows 8. The Android/SDK USB driver was installed correctly, but I forgot to install the USB driver from my phone. After installing the phone USB driver ADB works fine.
I hope this will help.

Turn on debugging in the Nexus settings Developer menu (tap "About Tablet" 7 times to get that menu).
Freaking Google tricks!

Have you had an android update recently? I updated to Lollipop and all the sudden I had no adb devices. Boo! I spent awhile trying a few things to no avail. Then I went into my developer options and lo and behold, "USB debugging" had been turned off. Silly Google. After turning it back on, it immediately showed up and I'm back in business!

GoTo DeviceManager, then right click on the android device and click uninstall driver.
Unplug and plug the device back...then a pop will come on your device while your pc installs the required drivers. Click "allow" on the popup.
You can see your device when you type "adb devices" in command prompt.

For Windows, just end all the processes related to Blue stacks or any such emulator if you are using.
Worked for me.

There's obviously a ton of different problems that could be causing this (and a ton of different solutions to go along with those problems). So think about all the solutions!
If you've gotten this phone and computer pair to work together before, but they aren't working any more, it might be a specific program on your computer rather than a problem on your phone. Some programs install/use their own adb, and only one of these can connect to your phone at a time. I think this makes a race condition, so sometimes it'll connect fine.
Some programs that run adb:
HTC Sync Manager - uninstall this.
chrome://inspect - lets you view localhost on your phone. Just close the window when you're done with it.

To have ADB in MTP mode
If you don't find any ADB device (nothing with exclamation mark) in the device manager (with all developers settings on phone checked), do this:
In Device Manager :
UpdateDriver->Manuel Install->Search on my computer->Select from installed driver list -> then select the one with the word usb in it (not MTP).
Edit: after that, you'll then have 2 or 3 peripheral, one for USB and one for ADB, install adb driver using usual method (see first answers)

For my Nexus 6P downloading drivers from Google helped resolved the issue. Here is the URL with documentation. And here you can download the driver itself.
P.S. I saw some people advice to download some drivers from random places on internet. While this might help it's too dangerous in my mind to download unknown drivers from unofficial places. So the one from Google worked well for me :)

How to connect the device to Eclipse?

I am not able to resolve this simple issue.
I am trying to connect my device to Eclipse via USB cable.
On my PC, I have installed Eclipse and the Android SDK and running the program on the emulator is working fine.
I have downloaded and installed Samsung Kies on my PC. It shows my device if connected via USB to the PC.
But I dont know how to connect the device with the emulator.
Connect means, I want to run the Eclipse code on my device instead of emulator. I am using Samsung Galaxy Ace GT-S5830i. Please help me out to resolve this issue.

Comment is lack of formatting so i add an answer.
Check if your computer had your phone driver. I assume that your use Windows. Open Device Manager
At a command prompt, in the Start Search box, or in the Run box, type the following command: mmc devmgmt.msc
. Other ways : check link
If you find your phone name or ADB Interface so you got driver. Try to restart DDMS or restart your Eclipse.
If you don't find your device or see something Other device with yellow question mark so try to install driver by browsing on your phone to Settings - Developer Options - Enable developer option - Enable USB debugging - Plug your phone to computer. Windows will ask you to install driver.
3, Update Google USB driver in Android SDK Manager (in Eclipse) or search Samsung Galaxy Ace GT-S5830i driver
4.Some weird case i got on some device.
Nexus S: disable Developer option. Restart phone. Enable again. Windows ask to install driver or you will see it in Eclipse.
HTC phone or Samsung : change Connectivity Option on phone to Charge only (Swipe status bar. Check notifications displayed). Some phone set it to some kind of Sync data so Windows can not recognize device.

I think your emulator is in Automatic. You can change that to Manual.
Try this,
Step 1
Go to Run Configuration
You can see three Columns Android,Target and Common.
Step2
Select the Target
Step 3
Choose Always prompt to pick device.Click Ok
Step 4
Now run your project you should see the emulator and your device. Select your device and click ok.
Hope it helps.

Source.
Troubleshooting
This all sounds very straightforward, but there are countless quirks and hard-to-diagnose problems that can make connecting a device much more difficult than it sounds. In this section, we'll run through a checklist of things to try when your device isn't registering.
Check that USB Debugging is enabled. This setting can inadvertently (and perhaps even automatically) change when you plug/unplug your device from your machine, or when you reboot your phone.
Check your device while it's connected to your machine. Is it asking you to choose between different modes? Some phones have a 'charge only' mode that can prevent Eclipse from recognizing the device.
Choose a connection type
Make sure you don't have an Android Virtual Device running in the background.
Could there be a problem with the USB cable? If you have a spare cable to hand, plug it in to rule out a fault with the cable itself.
Double-check you're running the correct driver. Even if you are, some devices have all the required software pre-installed (for example, HTC Sync) and downloading drivers from another location can muddy the waters. If this might be the case with your device, try uninstalling the driver from your machine and reinstalling the software from your device's memory.
Does the driver require supporting software? Samsung Kies on Windows requires .Net Framework 3.5 SP1 or above, for example. This is usually installed along with the driver, but there's no guarantee.
Running the Android Debug Monitor tool (monitor.bat) has been known to kickstart Eclipse into recognizing a new device. Connect your device, locate monitor.bat (android-sdks/tools/monitor.bat) and double-click to open. This will open the Android Debug Monitor, a stand-alone debugging tool that lists connected devices.
Android Debug Monitor
A running adb.exe process can interfere with the connection. Close Eclipse, and open the Task Manager by pressing CTRL, Shift and Esc. Find the adb.exe process and kill it. Launch Eclipse and try again.
Check that your 'Project Build Target' is compatible with the Android version on your device. You can check what version of Android your device is running by opening 'Settings' and selecting 'About Phone,' followed by the 'Software information' option if available. If you need a reminder of your project's build target, ensure the project is selected in Eclipse's 'Package Explorer,' open the 'Project' menu and select 'Properties.' If the 'Android' tab isn't selected by default, open it and the Build Target will be displayed.

Have you enabled USB debugging in your device?? You can find it in your device
Settings -> Developer Options -> USB Debugging.

The android app you have created will be a .apk file, generated by eclipse, during a successful Run. Find the .apk file from the eclipse project explorer or by tracing your workspace. Copy the .apk file to your memory card (via USB or a card reader) and install it.
You should also enable the "Unknown Sources" option under "Security" of your Android device.

If you have required options enabled on your phone (USB Debugging and Unknown Sources) you can try do this. On your computer open command console. Using cd navigate to your android sdk installation folder. Go to platform-tools. You should have there adb file. Run this
./adb kill-server
and then
./adb start-server
Then check plugged devices
./adb devices

First, you are not connecting device with emulator. What you want is eclipse to identify your device and use it for development.
Everything about using devices for android development is given in official documentation.

You have to put the phone in 'debug' mode - I don't have the instructions handy (but you can search here or on the android site for the info you need).
Also check for THIS.

Try right clicking the project -->Run As --> Run Configurations then select target and choose always prompt
On your device turn on debug mode
Now try running project

I am assuming you don't mean connecting the device with the emulator but connecting the device to your computer so you can debug it and run applications directly from Eclipse to the device. In which case KIES by Samsung will not help you at all. What you need is the Android USB Drivers provided in the Extras tab in SDK. Sometimes the installation will bug up because you didn't run SDK manager as an administrator so make sure you do that. When all of this is done make sure your device is unconnected to your computer and then reconnect it after the drivers are installed. You should be prompted with a new device installation wizard which you must accept. Additionally, you should have debugging enabled on your device, and as an extra step you can setup launching as a manual configuration but it is not needed.
To enable device debugging
Settings -> Developer Options -> USB Debugging.
For more information visit here
BTW : If the Google USB Drivers don't work you might need to install the specific Samsung drivers which are located here

Goto -> Setting -> Application -> Development -> USB Debugging
Enable it and try.

I know this is a little old, but I was having the same issue. I tried all the options of setting usb debugging (off), disconnecting, restarting phone, usb debugging (on), connecting the phone and it just wouldn't connect.
I ended up installing the latest version of Kies on my machine and added the Unified option at the end of the installer and I then the phone would connect. (Not sure i needed the unified option) but it worked for me.

I tried all the above but it didn't helped me. I did couple of things additionally
Since my mobile device is Android, I unchecked Unified option from Kies installer. This is the crucial thing that helped me solve my problem
I restarted my mobile phone.