For experienced readers:
- Find the Java path; it looks like this:
- Start-menu search for “environment variable” to open the options dialog.
PATH. Remove old Java paths.
- Add the new Java path to
- Close and re-open console/IDE.
You have encountered one of the most notorious technical issues facing Java beginners: the
'xyz' is not recognized as an internal or external command... error message.
In a nutshell, you have not installed Java correctly. Finalizing the installation of Java on Windows requires some manual steps. You must always perform these steps after installing Java, including after upgrading the JDK.
Environment variables and
(If you already understand this, feel free to skip the next three sections.)
When you run
javac HelloWorld.java, cmd must determine where
javac.exe is located. This is accomplished with
PATH, an environment variable.
An environment variable is a special key-value pair (e.g.
windir=C:\WINDOWS). Most came with the operating system, and some are required for proper system functioning. A list of them is passed to every program (including cmd) when it starts. On Windows, there are two types: user environment variables and system environment variables.
You can see your environment variables like this:
C:\>set ALLUSERSPROFILE=C:\ProgramData APPDATA=C:\Users\craig\AppData\Roaming CommonProgramFiles=C:\Program Files\Common Files CommonProgramFiles(x86)=C:\Program Files (x86)\Common Files CommonProgramW6432=C:\Program Files\Common Files ...
The most important variable is
PATH. It is a list of paths, separated by
;. When a command is entered into cmd, each directory in the list will be scanned for a matching executable.
On my computer,
C:\>echo %PATH% C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPower Shell\v1.0\;C:\ProgramData\Microsoft\Windows\Start Menu\Programs;C:\Users\craig\AppData\ Roaming\Microsoft\Windows\Start Menu\Programs;C:\msys64\usr\bin;C:\msys64\mingw64\bin;C:\ msys64\mingw32\bin;C:\Program Files\nodejs\;C:\Program Files (x86)\Yarn\bin\;C:\Users\ craig\AppData\Local\Yarn\bin;C:\Program Files\Java\jdk-10.0.2\bin;C:\ProgramFiles\Git\cmd; C:\Program Files\Oracle\VirtualBox;C:\Program Files\7-Zip\;C:\Program Files\PuTTY\;C:\ Program Files\launch4j;C:\Program Files (x86)\NSIS\Bin;C:\Program Files (x86)\Common Files \Adobe\AGL;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Intel\iCLS Client\; C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files (x86)\Intel\iCLS Client\;C:\Users\craig\AppData\Local\Microsoft\WindowsApps
When you run
javac HelloWorld.java, cmd, upon realizing that
javac is not an internal command, searches the system
PATH followed by the user
PATH. It mechanically enters every directory in the list, and checks if
javac.bat, etc. is present. When it finds
javac, it runs it. When it does not, it prints
'javac' is not recognized as an internal or external command, operable program or batch file.
You must add the Java executables directory to
JDK vs. JRE
(If you already understand this, feel free to skip this section.)
When downloading Java, you are offered a choice between:
- The Java Runtime Environment (JRE), which includes the necessary tools to run Java programs, but not to compile new ones – it contains
- The Java Development Kit (JDK), which contains both
javac, along with a host of other development tools. The JDK is a superset of the JRE.
You must make sure you have installed the JDK. If you have only installed the JRE, you cannot execute
javac because you do not have an installation of the Java compiler on your hard drive. Check your Windows programs list, and make sure the Java package’s name includes the words “Development Kit” in it.
(If you weren’t planning to anyway, feel free to skip this section.)
Several other answers recommend executing some variation of:
C:\>:: DON'T DO THIS C:\>set PATH=C:\Program Files\Java\jdk1.7.0_09\bin
Do not do that. There are several major problems with that command:
- This command erases everything else from
PATHand replaces it with the Java path. After executing this command, you might find various other commands not working.
- Your Java path is probably not
C:\Program Files\Java\jdk1.7.0_09\bin– you almost definitely have a newer version of the JDK, which would have a different path.
- The new
PATHonly applies to the current cmd session. You will have to reenter the
setcommand every time you open Command Prompt.
Points #1 and #2 can be solved with this slightly better version:
C:\>:: DON'T DO THIS EITHER C:\>set PATH=C:\Program Files\Java\<enter the correct Java folder here>\bin;%PATH%
But it is just a bad idea in general.
Find the Java path
The right way begins with finding where you have installed Java. This depends on how you have installed Java.
You have installed Java by running a setup program. Oracle’s installer places versions of Java under
C:\Program Files\Java\ (or
C:\Program Files (x86)\Java\). With File Explorer or Command Prompt, navigate to that directory.
Each subfolder represents a version of Java. If there is only one, you have found it. Otherwise, choose the one that looks like the newer version. Make sure the folder name begins with
jdk (as opposed to
jre). Enter the directory.
Then enter the
bin directory of that.
You are now in the correct directory. Copy the path. If in File Explorer, click the address bar. If in Command Prompt, copy the prompt.
The resulting Java path should be in the form of (without quotes):
You have downloaded a .zip containing the JDK. Extract it to some random place where it won’t get in your way;
C:\Java\ is an acceptable choice.
Then locate the
bin folder somewhere within it.
You are now in the correct directory. Copy its path. This is the Java path.
Remember to never move the folder, as that would invalidate the path.
Open the settings dialog
That is the dialog to edit
PATH. There are numerous ways to get to that dialog, depending on your Windows version, UI settings, and how messed up your system configuration is.
Try some of these:
- Start Menu/taskbar search box » search for “environment variable”
- Win + R »
- Win + R »
SystemPropertiesAdvanced.exe» Environment Variables
- File Explorer » type into address bar
Control Panel\System and Security\System» Advanced System Settings (far left, in sidebar) » Environment Variables
- Desktop » right-click This PC » Properties » Advanced System Settings » Environment Variables
- Start Menu » right-click Computer » Properties » Advanced System Settings » Environment Variables
- Control Panel (icon mode) » System » Advanced System Settings » Environment Variables
- Control Panel (category mode) » System and Security » System » Advanced System Settings » Environment Variables
- Desktop » right-click My Computer » Advanced » Environment Variables
- Control Panel » System » Advanced » Environment Variables
Any of these should take you to the right settings dialog.
If you are on Windows 10, Microsoft has blessed you with a fancy new UI to edit
PATH. Otherwise, you will see
PATH in its full semicolon-encrusted glory, squeezed into a single-line textbox. Do your best to make the necessary edits without breaking your system.
PATH. You almost definitely have two
PATH variables (because of user vs. system environment variables). You need to look at both of them.
Check for other Java paths and remove them. Their existence can cause all sorts of conflicts. (For instance, if you have JRE 8 and JDK 11 in
PATH, in that order, then
javac will invoke the Java 11 compiler, which will create version 55
.class files, but
java will invoke the Java 8 JVM, which only supports up to version 52, and you will experience unsupported version errors and not be able to compile and run any programs.) Sidestep these problems by making sure you only have one Java path in
PATH. And while you’re at it, you may as well uninstall old Java versions, too. And remember that you don’t need to have both a JDK and a JRE.
If you have
C:\ProgramData\Oracle\Java\javapath, remove that as well. Oracle intended to solve the problem of Java paths breaking after upgrades by creating a symbolic link that would always point to the latest Java installation. Unfortunately, it often ends up pointing to the wrong location or simply not working. It is better to remove this entry and manually manage the Java path.
Now is also a good opportunity to perform general housekeeping on
PATH. If you have paths relating to software no longer installed on your PC, you can remove them. You can also shuffle the order of paths around (if you care about things like that).
Now take the Java path you found three steps ago, and place it in the system
It shouldn’t matter where in the list your new path goes; placing it at the end is a fine choice.
If you are using the pre-Windows 10 UI, make sure you have placed the semicolons correctly. There should be exactly one separating every path in the list.
There really isn’t much else to say here. Simply add the path to
PATH and click OK.
While you’re at it, you may as well set
JAVA_HOME as well. This is another environment variable that should also contain the Java path. Many Java and non-Java programs, including the popular Java build systems Maven and Gradle, will throw errors if it is not correctly set.
JAVA_HOME does not exist, create it as a new system environment variable. Set it to the path of the Java directory without the
bin/ directory, i.e.
Remember to edit
JAVA_HOME after upgrading Java, too.
Close and re-open Command Prompt
Though you have modified
PATH, all running programs, including cmd, only see the old
PATH. This is because the list of all environment variables is only copied into a program when it begins executing; thereafter, it only consults the cached copy.
There is no good way to refresh cmd’s environment variables, so simply close Command Prompt and open it again. If you are using an IDE, close and re-open it too.