What can I do when I keep receiving the error
'javac' is not recognized as an internal or external command, operable program or batch file
when I want to compile my jar or .class file?
Thanks
Make sure %JAVA_HOME%/bin is on your %PATH% (or $JAVA_HOME on the $PATH in *nix).
It means that it is not in your path. You have the following options:
1) Change to the directory where javac lives before calling it.
2) Use the full path to javac when making the call, e.g. C:\java\jdk1.6.0_12\bin\javac ...
3) Add the javac directory to the PATH environment variable
This just means that javac isn't in your PATH variable.
On Windows, you just have to add the folder that contains javac.exe to the PATH environment variable (Win+Pause/Break).
On Linux/Mac/Unix, just append that directory to $PATH in .bashrc or similar.
The error that you are seeing is generated by Windows, and isn't specific to Java. That error means that you typed a command and Windows could not find the command by that name.
The easiest way of rectifying the situation is to ensure that Java is properly installed in your system's PATH.
First, ensure that you have a JDK installed (and not just a JRE). Your next best bet is to add an environment variable called JAVA_HOME and point it at the base install directory for the version of Java that you installed.
Next, modify your PATH environment variable by prepending the string %JAVA_HOME%\bin; to whatever is already in your PATH. If you look at the contents of that directory, you will see that javac is in there (along with a number of other Java development tools).
You have to install JDK (which includes javac compiler) and ensure that it's in the path. See http://java.sun.com/javase/downloads/index.jsp
Common Error Messages from SUN Tutorial page
Step 4 (Update the PATH variable) of the JDK installation instructions explains what you should do to make it so that you can just type javac in the command prompt window.
The link below gives a step by step explanation on how to set up java_home and path variables.
JAVA_HOME setup
Even if I had
JDK installed
JAVA_HOME defined
%JAVA_HOME%\bin present in my %PATH%
I still had this error. I resolved it by eliminating the JRE from my path variable. It was put before JAVA_HOME, has no javac. It seems Windows can't find javac in JAVA_HOME\bin in this case.
For Windows
Control Panel > System...Then click Advanced System Setting (left pane)...then popup window will open...then click Environment Variables...Then another window will open...click New and add enter information below
Variable name: PATH
Variable value: C:\Program Files\Java\jdk1.7.0_45\bin [*make sure this is the right path for you]
Then it should work
Check whether you have JDK installed; if not installed, Install
If JDK is installed, navigate into the bin folder of the installation, and try to execute javac.
If javac executes, proceed (+:
If javac does not execute, check your system path, and java path, and return to 2 above!
Related
I have installed Java 8 and set my JAVA_HOME and JRE_HOME paths and added %JAVA_HOME% to the start of the path variable.
I created a helloworld.java application and am able to compile it using:
javac helloworld.java
However, when I try to run:
java helloworld
I get the error:
The system cannot find the file C:\ProgramData\Oracle\Java\javapath\java.exe
How can I solve this?
1.Just go to C:\ProgramData\Oracle\Java\javapath\
2.You will find there shortcuts for java.exe,javaw.exe,javaws.exe which are pointing to a location where they actually are not existing now
3.Go to the jre location where you have installed java like C:\Program Files\Java\jre6\bin
You will find java.exe,javaw.exe,javaws.exe
Create shortcuts for these files and replace with the ones which are present in C:\ProgramData\Oracle\Java\javapath.
It works
Just set %JAVA_HOME%/bin to your path variable.
If you are blocked from modifying system variables from command line, but are able to open up an elevated command prompt, then run a command like this:
setx \M JAVA_HOME "C:\Program Files\Java\jdk1.8.0_25"
But of course, change the directory to point to your installed version of java. Note that the JAVA_HOME path does not point into the bin directory, it stops one level above bin.
I was able to solve this issue. To do so I used the advice from this answer:
Java SE Development Kit 8u25 on a 64-bit Windows 8
Set the following user environment variables (== environment variables of type user variables)
•JAVA_HOME : C:\Program Files\Java\jdk1.8.0_25
•JDK_HOME : %JAVA_HOME%
•JRE_HOME : %JAVA_HOME%\jre
•CLASSPATH : .;%JAVA_HOME%\lib;%JAVA_HOME%\jre\lib
•PATH : your-unique-entries;%JAVA_HOME%\bin
(make sure that the longish your-unique-entries does not contain any other references to another Java installation folder.)
Recently, when trying to compile java programs from the command prompt, I get this error:
Error: Cannot find or load main class com.sun.tools.javac.Main
I have the latest versions of the JDK and JRE, and I still get the error.
Here is what I type in the command line:
C:\Java_Source_Codes>javac hi.java
Can anyone help?
(Here is my java code)
public class hi{
public static void main(String[] args){
System.out.println("hello, world!");
}
}
You have a number of issues, Kumar mentioned the compilation issue, but that's not the immediate problem that's stopping you.
You have JAVA_HOME set to a Java Runtime environment, but are finding javac on the system PATH. When this happens, you can call javac from the command line, but when javac detects the JAVA_HOME environmental variable, it loads its libraries from a directory that doesn't include the "java tools", tools.jar. The contents of "java tools" includes the classes that implement the compiler.
You probably have JAVA_HOME set to something like /some/path/here/jre. Assuming that the jre directory is the embedded JRE shipped with your JDK, you probably should have set the JAVA_HOME to /some/path/here.
You need to have your PATH variable set up with a path to Java tools needed for compilation.
You need to have these folders in Path system variable.
D:\Program Files\Java\jdk1.6.0_32\jre;D:\Program Files\Java\jdk1.6.0_32\bin
Just replace D:\Program Files\Java with the folder you have installed Java on your computer.
Also, if you are using any other verion of JDK, replace jdk1.6.0_32 with your own.
This is due to some issue with your PATH.
Quick guess is you have multiple version of java on your PATH
Set the Path to the bin directory of the jdk in your system..
Try typing java -version on the cmd to see if your Java path is properly set.
Mine is..
C:\Program Files\Java\jdk1.7.0\bin
I had the similar problem but found a simple solution that might work in your case too.
My problem was I simply made a new folder in c directory to save my *.java files (like a test folder) and set my PATH to ...jdk\bin folder.
When I try to compile in cmd I got the same error main class not found.
So i went to environment variable and in user variable, where I saw my CLASSPATH pointing to same folder. So I changed my CLASSPATH to folder having my files in my case C:\test and the problem was solved.
Hope this helps.
OK, what am I doing wrong, this is driving me nuts.
I am trying to install the latest JDK (1.6.0_23). So, I downloaded it from Oracle's awful site and then ran the installation. I installed it to C:\Java\jdk1.6.0_23
Then, I created a JAVA_HOME User Variable that pointed to C:\Java\jdk1.6.0_23. I then added a piece to the end of my Path environment variable that says %JAVA_HOME%\bin.
However, when I try to simply open a command prompt and run simple java commands, I am told it is not a recognizable command. I have to manually cd into the that bin directory to do anything.
Do I also need a Classpath variable that points to the JRE? I noticed there was a Classpath variable there previously that pointed to jre/lib/QTJava.zip, but I deleted it.
If you have the JDK installed and a JAVA_HOME variable setup, do I still need the JRE in the classpath? I am running Windows 7 and do all of my development in Eclipse.
Maybe the problem is because you set JAVA_HOME as a user variable, but trying to reference it from the PATH which is a system variable (or is it?). You cannot do this, because system variables are evaluated before user variables.
There are two possible solutions:
1. Set JAVA_HOME as a system variable instead
2. Create a new user variable PATH and set %JAVA_HOME%\bin there. The user PATH and the system PATH variables will be concatenated at runtime automatically.
From http://social.answers.microsoft.com/Forums/en-US/vistainstall/thread/48b23109-9fbc-47c5-a5d1-465773f94704
(at the end)
1) Enable 'delayed variable expansion'
in the registry (see
http://batcheero.blogspot.com/2007/06/how-to-enabledelayedexpansion.html)
2) Change the '%' signs around var2 to
'!', e.g. "%var2%" becomes "!var2!"
I've done some limited testing on
Windows 7 and this appears to fix the
problem.
Maybe try that, see if it fixes it (I don't have windows here to try)
Do I also need a CLASSPATH variable that points to the JRE?
Strictly speaking, no. The CLASSPATH variable may be used if you try to run a java class and you don't use the -cp or -jar options.
The CLASSPATH variable doesn't need to point to the JRE. The java.exe command etc all know where to find the JRE's runtime classes. (And they don't look on the CLASSPATH for them anyway.)
For the PATH problem, try running:
C:\Java\jdk1.6.0_23\bin\java.exe -version
If that doesn't work then there's a problem with your actual installation. If it does work, try looking at what JAVA_HOME and PATH are set to in the environment variables of the command shell.
When running an ivy resolve via IvyDE in Eclipse, which contains a packager.xml that executes a javac ant task, I get the following:
Unable to find a javac compiler;
com.sun.tools.javac.Main is not on the
classpath. Perhaps JAVA_HOME does not
point to the JDK. It is currently set
to "C:\Program
Files\Java\jdk1.6.0_22\jre"
at org.apache.tools.ant.taskdefs.compilers.CompilerAdapterFactory.getCompiler(CompilerAdapterFactory.java:108)
In eclipse.ini I have
-vm
C:\Program Files\Java\jdk1.6.0_22\bin\javaw.exe
and in Help - About Eclipse - Installation Details - Configuration I see
java.home=C:\Program Files\Java\jdk1.6.0_22\jre
How can I make java.home point to C:\Program Files\Java\jdk1.6.0_22 instead?
Eclipse uses its own javac implementation internally. Therefore for most of the purpose you just need a compatible JRE. But javac task in ANT considers the JAVA_HOME or check for the local path variable. On windows machine as temporary fix you can do:
Open a command prompt
then type
SET path=C:\Program Files\Java\jdk1.6.0_22\;%path% hit enter
then type
<eclipsehome>\eclipse.exe
Now any process spawned from your eclipse will have your JDK version in the path variable.
for a permanent solution..
1. go to advance system setting
2. select advanced tab
3. select environment variables
4. modify the system path variable and JAVA_HOME (if required)
You can do the similar thing for *nix system (just check how to set environment setting on them)
Hope this will work.
UPDATE
The PROJECT classpath isn't the same as the ANT classpath. To set up an Ant classpath, navigate to window->preferences->ant->runtime here check whether the Global Entries points to C:\Program Files\Java\jdk1.6.0_22\lib\tools.jar if not then add it. Normally it works in most of the cases where ant cries for javac task. if it fails then please check whether some other script is not resetting your JAVA_HOME variable and ANT global entries setting.
If IvyDE is not using the ANT bundled with eclipse as plugin (and referring to some standard installation) or if you have defined a environment variable like ANT_HOME then copy
tools.jar file from C:\Program Files\Java\jdk1.6.0_22\lib\ to ANT_HOME\lib.
Also check this previous SO post ( Ant can't find Javac. No matter what I do it always claims JAVA_HOME is "C:\Program Files\Java\jre6" )
UPDATE 2
ok..
Check this page... http://ant.apache.org/ivy/ivyde/history/latest-milestone/preferences.html
Order of the classpath entries: By
default, the classpath container
entries are ordered by order of
declaration in the ivy.xml. When there
are many entries, it can be useful to
have them ordered lexically for
enhanced readability.
Is tools.jar present in ivy.xml? please check once.
I installed java on my machine and I wanted to compile this group of source code. But when I opened up the command prompt and typed in javac, the command prompt said it was an unknown parameter. The same thing happened when I wanted to build something with ant (I had the build.xml if you are wondering) and the same thing happened. How can I set the javac and ant command to be used in any directory?
First of all you have to be sure you installed JDK and not only JRE
Secondly it depends on your operating system:
windows: you have to reach environment variables by using My Computer (manage->advanced->something here)
linux/osx: you have to export variables with export command or by using a .profile file in user directory
Then you need to set two things:
adding /jdk_1.6.../bin/ to your PATH variable
setting JAVA_HOME to your root of java installation ( /java_1.6..../ ) (maybe this is not required by java itself but many frameworks use it)
One note: on OSX, and maybe Linux too you have to split paths in PATH variable with double colon ':' instead that semicolon ';'
Add the directory the executable is in to the PATH environment variable.
Guessing that you are using Windows. Right click My Computer and click Manage. Then, in the Advanced tab, select Environment Variables. In the new window, under System variables, find Path and append the full path to the binaries (javac and ant) at the end, separated by semicolons.