Develop Reference

java_home is not set and no 'java' command could be found in your path error while developloing react native app for andriod in windows

i am trying to develope react native android app ,when i run cmd ->
react-native run-android
IT SHOWS ERROR
C:\Windows\System32\PropertyFinder>react-native run-android
info JS server already running.
info Building and installing the app on the device (cd android && gradlew.bat app:installDebug)...
ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
Please set the JAVA_HOME variable in your environment to match the
location of your Java installation.
error Could not install the app on the device, read the error above for details.
Make sure you have an Android emulator running or a device connected and have
set up your Android development environment:
https://facebook.github.io/react-native/docs/getting-started.html
error Command failed: gradlew.bat app:installDebug. Run CLI with --verbose flag
for more details.

installation failed with message install_failed_uid_changed

I am running android app from android studio but failed to installed. Although I have uninstalled the app from mobile and have enough memory space in the mobile.
. Please What should I do. I have attached the alert .
Thanks

If your device is rooted you can try deleting your application's data from the device. To do so, delete /data/data/[app package name] folder or run adb shell rm /data/data/<app-package-name>. Then, try to install your app again.

For non-rooted device:
Change the ApplicationId of the app. Refer this link to change ApplicationId.
Build and install the app. The app will install successfully because it is treated as the new app.
Now uninstall this app which will clear the data.
Now change the ApplicationId to the previous one.
Build and install. It will install.
For rooted device:
Just delete
"/data/data/your.package.name"
on your device

Android Studio emulator: "Could not access the Package Manager." and "AdbCommandRejectedException: device 'emulator-5556' not found"

I've got a problem with the emulator in Android Studio. I took the version with the ARM Systems Image.
When I started the app, this error came into the run-app console on the bottom:
Target device: Nexus_S_API_23_2_ARM [emulator-5556]
Installing APK:C:\Users\Martin\AndroidStudioProjects\MyApplication4\app\build\outputs\apk\app-debug.apk
Uploading file to: /data/local/tmp/com.example.martin.myapplication.app
Installing com.example.martin.myapplication.app
DEVICE SHELL COMMAND: pm install -r "/data/local/tmp/com.example.martin.myapplication.app"
Error: Could not access the Package Manager. Is the system running?
DEVICE SHELL COMMAND: pm uninstall com.example.martin.myapplication.app
DEVICE SHELL COMMAND: pm install -r "/data/local/tmp/com.example.martin.myapplication.app"
com.android.ddmlib.AdbCommandRejectedException: device 'emulator-5556' not found

I would suggest you to use Genymotion emulator. Its fast as compared to the emulator provided by Android studio. Search about Genymotion. Its really awesome

Cannot be root on Android Emulator

I'm currently trying to develop an application for Android devices on an Android Emulator. I installed Android 4.3 on a VMWare Workstation, on a Windows 10 OS.
I want to test the app I'm developping on the Android emulator, so I have to create a bridge connection between my phyisical computer where I develop the aps, and the emulator, where I can test it. But when I try to create this bridge, I have to change settings and to be root of the emulator. When I try to do a 'su' command, I have the following error :
'su : uid 10000 not allowed to su'
I tried to follow this tutorial to give me the root acces of the emulator, but it didn't worked for me. The best answer is to execute this commands :
adb shell mount -o rw,remount -t yaffs2 /dev/block/mtdblock03 /system
adb push su /system/xbin/su
adb shell chmod 06755 /system
adb shell chmod 06755 /system/xbin/su
How to get root access on Android emulator?
More over, When I did the installation of the Android Emulator, I've done the installation specifying the read-write option.
It is not working for me, because when I try the first row, I obtain this message :
ADB error : 'device not found'
Such as it is described in this link :
How to fix: Error device not found with ADB.exe
But the answer exists for a phone, and not for an emulator. Do you know how to fix it ? How can I be root, and how can I found the 'device not found' ?
Here are the different parameters of the VM

su stands for super users which is available only on rooted device. it is more like using android application with administrator privilege.Try using BLuestacks rooted version.

Eclipse doesn't find my already running Android emulators

Configuration
Os: OSX
IDE: Eclipse Juno
I don't know why but when I try to run again my Android app, the "Android Device Chooser" frame opens but my emulators are not shown in "Choose a running Android device" section. What should I do ?

Goto the DDMS view and try resetting the ADB as shown---

Please check the required API levels of the application and than on the device.
Try to run following commands in terminal that will renew the adb server state :
adb kill-server
adb start-server
You can try to use adb over the wifi and than no cables will needed.