View source for Unable to find a javac compiler

In Tomcat, Jetty, or another servlet container, you may receive an error stating the javac compiler can't be found.  The obvious reason is if you are running from a JRE and not a JDK, however, it can still happen even when running a JDK.

The following is a typical error message:
<geshi>
HTTP ERROR: 500

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 "/java/jdk1.6.0_17/jre"

RequestURI=/web/
Caused by:

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 "/app/java/jdk1.6.0_17/jre"
	at org.apache.tools.ant.taskdefs.compilers.CompilerAdapterFactory.getCompiler(CompilerAdapterFactory.java:108)
	at org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:1058)
	at org.apache.tools.ant.taskdefs.Javac.execute(Javac.java:882)
	at org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:382)
	at org.apache.jasper.compiler.Compiler.compile(Compiler.java:472)
	at org.apache.jasper.compiler.Compiler.compile(Compiler.java:451)
	at org.apache.jasper.compiler.Compiler.compile(Compiler.java:439)
	at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:511)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:295)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:502)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:363)
	at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
	at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
	at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:757)
	at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:416)
	at org.mortbay.jetty.servlet.Dispatcher.forward(Dispatcher.java:334)
	at org.mortbay.jetty.servlet.Dispatcher.forward(Dispatcher.java:126)
	at org.mortbay.jetty.servlet.DefaultServlet.doGet(DefaultServlet.java:463)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
</geshi>

You can verify the running JVM properties using the '''jinfo''' command.  Example:

<geshi>
/java/jdk1.6.0_17/bin/jinfo -sysprops 26314 | grep java.home
Attaching to process ID 26314, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 14.3-b01
java.home = /java/jdk1.6.0_17/jre
</geshi>

The easiest solution is to copy the '''tools.jar''' into the lib directory.

<geshi>
cp -p /java/jdk1.6.0_17/lib/tools.jar /java/jdk1.6.0_17/jre/lib/
</geshi>

[[Category:Java]]