Fixing “java is not recognized” after installing Java

You installed Java, typed java -version, and got 'java' is not recognized as an internal or external command — or on a Mac, command not found: java. The installer put Java on the disk but did not tell your terminal where to find it. Fixing that is a PATH entry and, for most tools, a JAVA_HOME variable.

What the error means#

When you type a command, the shell looks through a list of folders called the PATH. If none of them contains a file called java (or java.exe), you get this error. Java being installed somewhere on the disk is not enough; that folder has to be on the list.

Some installers add it for you. Many do not — particularly the plain JDK archives from Oracle, Adoptium and Microsoft.

Step 1: find where Java is#

# Windows - look in the usual places
dir "C:\Program Files\Java"
dir "C:\Program Files\Eclipse Adoptium"
dir "C:\Program Files\Microsoft"

# macOS - the JDK tool lists every installed version
/usr/libexec/java_home -V

# Linux
ls /usr/lib/jvm
update-alternatives --list java

You are looking for a folder containing a bin subfolder with java inside it. That parent folder is what JAVA_HOME should point to; the bin folder is what goes on the PATH.

Windows#

Do this through the settings dialog so it survives reboots:

1. Press the Windows key and type environment variables, then open Edit the system environment variables.
2. Click Environment Variables.
3. Under System variables, click New. Name: JAVA_HOME. Value: the JDK folder, for example C:\Program Files\Eclipse Adoptium\jdk-21.0.4.7-hotspot.
4. Select Path, click Edit, then New, and add %JAVA_HOME%\bin.
5. Click OK on every dialog.

Or from an administrator PowerShell:

[Environment]::SetEnvironmentVariable("JAVA_HOME", "C:\Program Files\Eclipse Adoptium\jdk-21.0.4.7-hotspot", "Machine")
$p = [Environment]::GetEnvironmentVariable("Path", "Machine")
[Environment]::SetEnvironmentVariable("Path", $p + ";%JAVA_HOME%\bin", "Machine")

macOS#

Modern macOS uses zsh, so the file to edit is ~/.zshrc:

echo 'export JAVA_HOME=$(/usr/libexec/java_home -v 21)' >> ~/.zshrc
echo 'export PATH="$JAVA_HOME/bin:$PATH"' >> ~/.zshrc
source ~/.zshrc
java -version

The java_home helper finds the requested version wherever the installer put it, which is why it beats a hard-coded path. Drop the -v 21 to get whatever is newest.

If you installed with Homebrew and it still is not found, Homebrew tells you the exact line to add at the end of its install output — run brew info openjdk to see it again. Usually it is a symlink into /Library/Java/JavaVirtualMachines.

Linux#

If you installed from your distribution’s package manager, it normally handles this. If you unpacked a tarball:

sudo mv jdk-21.0.4 /opt/
echo 'export JAVA_HOME=/opt/jdk-21.0.4' >> ~/.bashrc
echo 'export PATH="$JAVA_HOME/bin:$PATH"' >> ~/.bashrc
source ~/.bashrc

On Debian and Ubuntu with several versions installed, update-alternatives is the cleaner way to choose the default:

sudo update-alternatives --config java
sudo update-alternatives --config javac

Checking what you have#

java -version        # the runtime that will execute programs
javac -version       # the compiler - only present with a JDK, not a JRE
echo $JAVA_HOME      # macOS/Linux
echo %JAVA_HOME%     # Windows cmd
$env:JAVA_HOME       # PowerShell
where java           # Windows: every java.exe on the PATH, first one wins
which -a java        # macOS/Linux equivalent

If java works but javac does not, you installed a runtime rather than a development kit. Install a JDK; it includes both.

When it works in one terminal but not another#

This is almost always because the variable was set for the wrong scope:

• Windows: User variables apply to your account; System variables apply to everyone. Setting one and expecting it in an administrator prompt, or vice versa, is a common mismatch.
• macOS: zsh reads ~/.zshrc; bash reads ~/.bash_profile. Editing the wrong one does nothing. Check with echo $SHELL.
• VS Code and IntelliJ: launched from the Dock or Start menu, they may not inherit variables you set in a shell file. Log out and back in, or set the JDK inside the editor’s own settings as well.

Several versions installed#

Whichever bin folder comes first on the PATH wins. The where and which -a commands above show the order. If the wrong one is first, move your entry above it — on Windows, the PATH editor has Move Up buttons; on macOS and Linux, putting $JAVA_HOME/bin before $PATH in the export line does it.

If you switch versions often, a version manager is less painful than editing PATH by hand. SDKMAN on macOS and Linux and the Microsoft JDK installer on Windows both handle it.

Where to go next#

• Introduction to Java — what to do once the command works.
• Java not working in VS Code — the editor has its own JDK setting.
• Command line basics — what PATH actually is.