I am experiencing an error while trying to compile Java programs.
I am on Windows (this is a Windows-specific problem) and I have the latest JDK installed.
I have attempted a solution involving the PATH
variable, but the error persists.
Console output:
C:\>set path=C:Program Files (x86)\Java\jdk1.7.0\bin
C:\>javac Hello.java
'javac' is not recognized as an internal or external command,
operable program or batch file.
For experienced readers:
C:\Program Files\Java\jdkxxxx\bin\
PATH
. Remove old Java paths.PATH
.JAVA_HOME
.Welcome!
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.
PATH
(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, PATH
is:
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.com
, javac.exe
, 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 PATH
.
(If you already understand this, feel free to skip this section.)
When downloading Java, you are offered a choice between:
java
but not javac
.java
and 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.
set
(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:
PATH
and replaces it with the Java path. After executing this command, you might find various other commands not working.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.PATH
only applies to the current cmd session. You will have to reenter the set
command 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.
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):
C:\Program Files\Java\jdkxxxx\bin\
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.
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:
control sysdm.cpl,,3
SystemPropertiesAdvanced.exe
» Environment VariablesControl Panel\System and Security\System
» Advanced System Settings (far left, in sidebar) » Environment VariablesAny 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
Look at 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).
PATH
Now take the Java path you found three steps ago, and place it in the system PATH
.
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.
JAVA_HOME
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.
If 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. C:\Program Files\Java\jdkxxxx\
.
Remember to edit JAVA_HOME
after upgrading Java, too.
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.