Invoke Javac At Runtime
You can access javac programmatically, that is compile Java source code at runtime from a running program! The javac compiler is made available via the tools.jar in the lib directory from the JDK. To get started with the following example you will need to add the tools.jar to your project’s classpath. You can find tools.jar in the lib directory of your JDK installation path.
One you have tools.jar in you classpath, you can create an instance of com.sun.tools.javac.Main, the entry point for javac.
You can call the compile method on the javac instance passing in an array of strings as options. For example, here are the options that include the classpath and the output directory for the file to compile.
And of course you can use any of the other options such as -deprecation or -g. To compile a source file, just invoke compile as in the following code bit.
Compile Java this way can be helpful if your application generates one off statements that need to run in the system. I have used a mechanism like this to write what essentially is a script file but in Java code instead of Groovy or Jython. One thing to remember is that tools.jar is only available with the Java Development Kit, not the Java Runtime Environment.
Technorati Tags: java, runtime, javac, scripting, script, jre, jdk, compile, groovy, jython
Can I access reflection Information about a Java Class whose qualified name has not been given?
Please do let me know at your earliest.
I searched the web but in vain
By the way your article very much helped me, but I want the Java DOCs of this tools.jar API.
How to get it?
@Soham - AFAIK you need the qualified class name to load the class via the ClassLoader.
To you second question, try using the com.sun.tools.javadoc.Main class to invoke JavaDoc from your own code/classes in a similar manner which I described here.
how do print out the errors received after programmatically compiling?
Top Java SE 6 Features…
Now that I have had some time to work with Java SE 6, I thought I share a list what I think are the top five features….
Hi All,
PLEASE SUGGEST ME SOME TIPS….!
I have been trying since 3 days to solve this problem…every thing is fine with tools .jar, web.xml and every thing even classpath also
please kindly help me to solve this ….
HTTP Status 500 -
——————————————————————————–
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: java.lang.NoClassDefFoundError: sun/tools/javac/Main
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:481)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
com.auth.servlets.Controller.doPost(Controller.java:330)
com.auth.servlets.Controller.doGet(Controller.java:58)
javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
root cause
java.lang.NoClassDefFoundError: sun/tools/javac/Main
org.apache.jasper.compiler.SunJavaCompiler.compile(SunJavaCompiler.java:136)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:272)
org.apache.jasper.servlet.JspServlet.loadJSP(JspServlet.java:548)
org.apache.jasper.servlet.JspServlet$JspServletWrapper.loadIfNecessary(JspServlet.java:176)
org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:188)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:381)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:473)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
com.auth.servlets.Controller.doPost(Controller.java:330)
com.auth.servlets.Controller.doGet(Controller.java:58)
javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.13 logs.
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Apache Tomcat/6.0.13