[android] 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:

1. How could I find the internal Java inside the Android Studio folder so that I could point JAVA_HOME to it?
2. 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?

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

I think the right way to find the internal Java used by the Android Studio is to

1. Open Android Studio
2. Go to File->Other Settings->Default Project Structure/JDK Location:
3. 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

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

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

1. Make sure you have java installed
2. 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

3. 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

Windows 10:

Android Studio -> File -> Other Settings -> Default Project Structure... -> JDK location:

copy string shown, such as:

C:\Program Files\Android\Android Studio\jre

In 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 OK buttons to close out.

Some installations may require JRE_HOME to be set as well, 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 seems to support spaces in the filename paths for system variables very well, and does not seem to need ~tilde eliding.

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.

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 .

Please add the JAVA_HOME in the System variable no in the user variable

1. Create the Variable name as JAVA_HOME
2. Please use these format in the value box --> C:\Program Files\Java\jdk(version) what you have or downloaded.