Develop Reference

React Native: JAVA_HOME is not set and no 'java' command could be found in your PATH

I've followed step by step the official Getting Started. I started from a clean linux install and installed everything required as per the "Building Projects with Native Code" tab. I have also read the troubleshooting section. I've already created the project using the terminal.
This is the error when I run react-native run-android:
Starting JS server...
Building and installing the app on the device (cd android && ./gradlew 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.
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/android-setup.html
It does not find JAVA_HOME because the latest versions of Android Studio don't require Java to be installed in the system. Instead an internal JRE is used.
Duplicate disclaimer: I've already read this question. This is not what I want. I know how to set the Java home. I just want to run the react project WITHOUT having to install a separate Java.
Questions:
How could I find the internal Java inside the Android Studio folder so that I could point JAVA_HOME to it?
If not possible, could I open and run the project inside the android folder with Android Studio? How would I refresh this project after modifying the React JavaScript code in the parent folder?

Windows 10:
Android Studio -> File -> Other Settings -> Default Project Structure... -> JDK location:
copy string is shown, such as:
C:\Program Files\Android\Android Studio\jre
In the file locator directory window, right-click on "This PC" ->
Properties -> Advanced System Settings -> Environment Variables... -> System Variables
click on the New... button under System Variables, then type and paste respectively:
.......Variable name: JAVA_HOME
.......Variable value: C:\Program Files\Android\Android Studio\jre
and hit the OK buttons to close out.
Some installations may also require JRE_HOME to be set in the same way.
To check, open a NEW black console window, then type echo %JAVA_HOME%. You should get back the full path you typed into the system variable. Windows 10 supports spaces in the filename paths for system variables very well and does not need ~tilde eliding.

I'll answer my own questions and sponfeed my fellow linux users:
1- To point JAVA_HOME to the JRE included with Android Studio first locate the Android Studio installation folder, then find the /jre directory. That directory's full path is what you need to set JAVA_PATH to (thanks to #TentenPonce for his answer).
On linux, you can set JAVA_HOME by adding this line to your .bashrc or .bash_profile files:
export JAVA_HOME=<Your Android Studio path here>/jre
This file (one or the other) is the same as the one you added ANDROID_HOME to if you were following the React Native Getting Started for Linux. Both are hidden by default and can be found in your home directory. After adding the line you need to reload the terminal so that it can pick up the new environment variable. So type:
source $HOME/.bash_profile
or
source $HOME/.bashrc
and now you can run react-native run-android in that same terminal. Another option is to restart the OS. Other terminals might work differently.
NOTE: for the project to actually run, you need to start an Android emulator in advance, or have a real device connected. The easiest way is to open an already existing Android Studio project and launch the emulator from there, then close Android Studio.
2- Since what react-native run-android appears to do is just this:
cd android && ./gradlew installDebug
You can actually open the nested android project with Android Studio and run it manually. JS changes can be reloaded if you enable live reload in the emulator. Type CTRL + M (CMD + M on MacOS) and select the "Enable live reload" option in the menu that appears (Kudos to #BKO for his answer)

I think the right way to find the internal Java used by the Android Studio is to
Open Android Studio
Go to File->Other Settings->Default Project Structure/JDK Location:
and copy what ever string is specified there
This will not require memorising the folder or searching for java and also these steps wil take of any future changes to the java location by the Android Studio team changes I suppose

I'm using Ubuntu 20 on my machine, I have got the same problem the thing that worked for me was:
sudo apt-get install default-jre
you can verify that if the installation was successful or not by:
java --version
you are gonna see something like this in your terminal
openjdk 11.0.12 2021-07-20
OpenJDK Runtime Environment (build 11.0.12+7-Ubuntu-0ubuntu3)
OpenJDK 64-Bit Server VM (build 11.0.12+7-Ubuntu-0ubuntu3, mixed mode, sharing)

It is located on the Android Studio folder itself, on where you installed it.

Please add the JAVA_HOME in the System variable no in the user variable
Create the Variable name as JAVA_HOME
Please use these format in the value box --> C:\Program Files\Java\jdk(version) what you have or downloaded.

I fixed this issue by installing jre, I have jdk already installed but jre was not installed.

For those still not able to set JAVA_HOME from Android Studio installation, for me the path was actually not in C:\...\Android Studio\jre
but rather in the ...\Android Studio\jre\jre.
Don't ask me why though.
Environment variables jre location snippet

For ubuntu 16.0+
You can find the jre folder in android studio on this path /snap/android-studio/current/android-studio/jre
add the following line in your .bashrc or .bash_profile
export JAVA_HOME=/snap/android-studio/current/android-studio/jre
type
sudo nano $HOME/.bashrc
or
sudo nano $HOME/.bash_profile
after this execute the following line to in your terminal where you are executing the npx react-native run-android to reload the terminal with the new changes
source $HOME/.bashrc
or
source $HOME/.bash_profile

All I did is go to my project directory from the cmd (command prompt) I typed java -version.it told me what version it was looking for. so I Installed that version and I changed the path to were the jdk of that version was located .

apparently the system variables were not in sync with the user
variables
run as admin on command prompt and set the variable
i also saw some tips to close the node window and the vscode terminal for
the variable to take effect
tip from this site
https://confluence.atlassian.com/doc/setting-the-java_home-variable-in-windows-8895.html
setx -m JAVA_HOME "C:\Progra~1\Java\jdk1.8.0_XX"
and then
echo %JAVA_HOME%

For fish users:
Open ~/.config/fish/config.fish;
Include line set JAVA_HOME /home/ronald/Documents/android-studio/jre and set PATH $PATH $JAVA_HOME;
Re-open fish terminal.
Welcome :)

After adding the environmental variable , please restart the editor. It may save your ton of time.

Make sure you have java installed
your path is wrong
do this:
export | grep JAVA
THE RESULT: what java home is set to
JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_202.jdk/Contents/Home
follow the path to see if the directories are correct
i did this in my terminal:
open /Library
then i went to /Java/JavaVirturalMachines
turns out I had the wrong "jdk1.8.0_202.jdk" folder, there was another number...
4. you can use this command to set java_home
export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_202.jdk/Contents/Home

I ran this in the command prompt(have windows 7 os):
JAVA_HOME=C:\Program Files\Android\Android Studio\jre
where what its = to is the path to that jre folder, so anyone's can be different.

what I did to solve this on windows was to go to the environment variables and set the variable name to JAVA_HOME and then set the variable value to C:\Program Files\OpenJDK\openjdk-8u312-b07
then I set the path to C:\Program Files\OpenJDK\openjdk-8u312-b07\bin

From Android Studio, go to File, Settings, "Build, Execution, Deployment", Build Tools, Gradle. You should see the path to your JDK there, as visible in the screenshot (tested on Android Studio version 2020.3.1). Set an environment variable called JAVA_HOME containing that path (just google "set an environment variable" and followed by your Operating System name).

for those who are new to react native development
please set JAVA_HOME like this
instead of
C:\Program Files\Java\jdk1.8.0_301\bin
just remove "\bin" from path
C:\Program Files\Java\jdk1.8.0_301 after removing \bin

Guys after fight a lot to find the solution, including pass for many of that articles. I just realized that when you extract the Android SDK it doesn't come inside the folder cmdline-tools/latest and doesn't matter the place that I put the folder, opt/Androd_SDK, $HOME/Android_SDK the sequence of the error were the same. Until I got this error running:
➜ bin ./sdkmanager -version
Error: Could not determine SDK root.
Error: Either specify it explicitly with --sdk_root= or move this package into its expected location: /cmdline-tools/latest/
So, basic the solution was add the content of the SDK zip inside of the folders cmdline-tools/latest.
Once you do this, SDK and all the commands will work normally. Just don't forget to finish the configuration, like create the environment of the Android SDK, JAVA and so on.
An awesome article is that one:
https://medium.com/#khairold/setting-up-react-native-on-linux-without-android-studio-a65f3e011bbb
;)

if someone still facing similar issue and looking for an answer for the same? I would like to share the solution which worked for me. And by the way I haven't installed JAVA JDK/SDK in order to resolve the issue.
I am using Visual Studio code to develop react-native apps (using nox player for android app testing), I ran into the similar issue:
Issue:
$
› Building app...
$
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.
C:\Users...\android\gradlew.bat exited with non-zero code: 1
Resolution: In package.json file I have changed "main": "index.js" to "main": "node_modules/expo/AppEntry.js" it worked for me.
It would be great if this solution helps anyone, let me know for any additional information.

Make sure you have installed the following:
Java
JDK
JRE

If you use Ubuntu, maybe its helpful this tutorial. You have solution for how to solve error ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH..
There are many solutions found for Windows or Mac OS on internet to resolve this error. I'm using Ubuntu 22.10 kinetic
Solution:
Go to your Android Studio folder, find folder named jbr, copy all content folder, and if you don't have, create a folder named jre and copy in jre folder, all contents from jbr folder. Case close. Error solved.
java is not set
Video

How to set JDK path correctly in Android Studio

I am using Android Studio 1.4.1. when I tried to open an existing project, i received the follwoing error:
Error:The supplied javaHome seems to be invalid. I cannot find the java
executable. Tried location: C:\xxx\SDK\bin\java.exe
I do not know why Android Studion looks for the Java.exe in the SDK folder. the JDK path is specified as shown in the image
image:
This issue causes the all the classes of the App to be marked with a red circle with "j"letter.
Please let me know how to solve this issue

Try to set JAVA_HOME environment variable to something like this C:\Program Files\Java\jdk1.8.0_66.

In android studio
go to file
then choose PROJECT STRUCTURE
and go to JDK LOCATION
and choose current path of jdk
(e.g. /home/vishu/android-studio/jdk1.8.0_111)
if you do not have jdk downloaded
use this link-
http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
download according to your OS

Could not find tools.jar React Native Android In windows 10

guys . i just try to install react native in my laptop. i've followed all setup instruction but i stiil get those error .
* What went wrong:
Execution failed for task ':app:compileDebugJavaWithJavac'.
> Could not find tools.jar
i used genymotion with os version 5.1.0, i've setup environment variable for android_home. Any idea what i miss here ?

Setting the missing "JAVA_HOME" system environment variable worked for me.
Press WIN+Pause on keyboard.
Click advanced system settings.
Click "Environment variables".
Click "New" under "System variables".
Type "JAVA_HOME" in the Variable name field.
Type the path to the JDK in the Value field. For me the correct path
with short filename was "C:\PROGRA~1\Java\jdk1.8.0_66". Your path will vary depending on the installed version.
Click OK, and OK in previous window too.
Restart any command prompts or restart the computer.
react-native run-android worked fine after that.

Setting up appropriate JDK (not JRE. JRE does not have tools.jar) version (E.g. JDK 1.7x) path as the JAVA_HOME would resolve this issue.
Please check your computer's environment variables and set JAVA_HOME if it has not already been setup.

If you have the Android Studio embedded JDK, then it may cause conflicts. A workaround for this problem I've found is setting your JAVA_HOME to the default JDK location specified in Android Studio.
Open Android Studio
Press Ctrl+Alt+Shift+S to open Project Structure window.
Set your JAVA_HOME environment variable to the path specified under "JDK location".

I'm gonna go on a long shot here.
There is a tools.jar in java libs folder.[the java sdk that is]
Usually all these frameworks and ides have a lib folder themselves. and it is missing said tools.jar. Just copy paste it there.

I had the same problem while running react-native run-android it gave me the error tool.jar not found. i solved this by adding a single line mentioned below, in gradle.properties file which is in android project.
org.gradle.java.home=C:\Program Files\Java\jdk1.8.0_121

If this problem occurs for Windows, then the solution here is fairly simple.
Install Chocolatey
Follow the installation instructions on this page. https://chocolatey.org/install
Install jdk8
Restart Command Prompt or Powershell as Administrator, and run:
choco install jdk8
Now if you run
react-native run-android
This error shouldn't show up.

Find and copy tool.jar from JDK path
C:\Program Files\Java\jdk1.8.0_151\lib\tool.jar
then paste it in JRE folder
C:\Program Files\Java\jre1.8.0_181\lib
then delete build folder from your project/android/app/=>build
and then try react-native run-android

Just to add another data point for people pulling their hair out. I think a java update may have messed up my environment that was working fine 2 months ago. The combination of what worked for me:
Set JAVA_HOME to 1.7, NOT 1.8.
I had 2 1.8 versions installed and neither worked.

I know this question is for Windows, but this is the first result for this error on Google, so for Linux this problem could be fixed with:
sudo apt install default-jdk

I have deleted "\react_native_project_path\android" directory and run
reactive-native android
then run ..
reactive-native run-android
Then the error is gone

At first I have to tell you open your CMD Then write java -version then write javac -version Then see IF you haven't them press Win + pause then click on advance system setting then click on Environment variables then in system variables Click on New Then write JAVA_HOME in variable name and in the second section write your JDK path and click ok then in system variable click on path then click edit and then click on New and write %JAVA_HOME%\bin and click ok then ok and at the end if you want to check it open CMD again and write java -version and then javac -version I hope this will work for you.

Android Studio 1.2.2 issue with JAVA_HOME

I have installed JDK 1.8u45 in my machine. Earlier I was running Android Studio 1.1.0 in my machine with JAVA_HOME environment variable pointing to JDK bin directory. It was working perfectly fine. But, I recently updated Android Studio to 1.2.2 and I am getting error with JAVA_HOME as JAVA_HOME doesn't point to a valid JVM installation.
Someone had raised a question about the same issue at following location, but there is no response.
https://code.google.com/p/android/issues/detail?id=172277
Besides, known issues page at Android Studio page doesn't site this issue.
http://tools.android.com/knownissues
While I try to launch Android Studio, I get the above error.
Could anyone please help me with this?

Change the JAVA_HOME environment variable from C:\Program Files\Java\jdkx.x.x_xx\bin to C:\Program Files\Java\jdkx.x.x_xx
You don't need to navigate to bin folder.

Change environment variable JAVA_HOME to JDK_HOME and dont include bin folder in the path.
e.g JDK_HOME="C:\Program Files\Java\JDK 1.8u45 "

Gradle in Android Studio giving error Project sync failed

I am new to Android Studio.I installed Android Studio-1.2.1.1 and i have jdk1.7.0_40 installed.I am facing problem with gradle build.
For reference you can check gradle issue
I am getting following error in messages
Error:The newly created daemon process has a different context than expected.
Java home is different.
Expecting: 'C:\Program Files\Java\jdk1.7.0_40' but was: 'C:\Program Files\Java\jdk1.7.0_40\jre'.
Please configure the JDK to match the expected one.
Open JDK Settings
All i understood is gradle is using JRE and Android Studio is using JDK and due to that two JAVA_HOME's are different and giving errors.
I tried downloading gradle 2.3 and changed gradle path in android studio to this file,still same problem.

This is a very late answer but I see that a common suggestion is to remove all other jdk's and this is not always the best idea. You might need older jdk's for different projects. You can go into the gradle.properties file for the project and enter the following line (varied based on your version):
org.gradle.java.home=C:/Java/jdk1.8.0_111
If you are using a different jdk just point to a different directory.

Replace this
C:\Program Files\Java\jdk1.7.0_40\jre
with
C:\Program Files\Java\jdk1.7.0_40
inside your JAVA_HOME variable

EDIT:
I fixed this issue by uninstalling all the jdk installation & updates
then reinstall only one jdk and assure its env. variables
I do not have a solution but I have the same problem
it happens as the android studio opens from java_home/jre thence all JVMs that will fork next will come from this path, while your system varible tells Gradle to get his java.exe from JAVA_HOME
I tried to make gradle read from jre but it falied also i tried to make android studio open from java_home/bin but it falid also

For those who are on OS X El Capitan (v10.10) and end up with the above error message.
In my case there was nothing wrong with Gradle, simply my Java 1.8 was "too new" for Android Studio 1.5 so I had to install older 1.7.
I downloaded it from
http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html
(jdk-7u79-macosx-x64.dmg)
After all I had to just update JDK location in the project structure

I already had java jdk 7u17 and I also had got same error as FaizAli.
I try to search and done a lot of changes but not success!
Then, I downloaded jdk 7u80 at this link and installed this jdk.
After that those error gone.

I solved it by going to Project Structure then unchecking use embedded JDK and then setting the path to C:\Program Files\Java\jdk1.8.0_121

What I found out in my case is that the SDK my project pointed to "broke" and I had to fix its "JDK home path":

This is 2019.
For anyone experiencing this issue...
The first thing is to make sure that you correctly set your environment variables as per this instruction: https://www.mkyong.com/java/how-to-set-java_home-on-windows-10/
Which means you should be able to type javac -version and java -version and get the version number inside your Home directory.
Once you can confirm this, then go to the Project Structure inside, the SDK Location > JDK Location select Use JAVA_HOME environment variable.
This was what I did and it worked.

Solved this by going to
File -> Project Structure -> SDK Location
and under JDK Location, update with Gradle SDK location.

This happens because Android is using embedded ( JRE ) which is selected as recommended and at same time Android Studio detects JDK Home_Path (Environmental Variable ) and due to that two JAVA Path are different there is the conflict so it give you Error :
If You remove java_home path or Environmental variable you will get this error:
CreateProcess error=2, The system cannot find the file specified [Android studio
For Android Studio, the solution is to go to File> Other Setting > Default Project Structure> Uncheck the checkbox
and browse and set JDK path