For major Java programming, it is recommended to use a full Java IDE, however if you are just wanting to work with a couple Java classes, Lucee with the help of a third party library can compile Java classes.
To use the examples below, you'll need a copy of JAR file for the Eclipse IDE Java Compiler
The following Application .cfc will compile any Java classes it finds in its containing folder
```
component {
this.javaSettings = {LoadPaths = ["./"], loadCFMLClassPath = true, reloadOnChange= true, watchInterval = 2, watchExtensions = "jar,class,xml"}
function onRequestStart(){
compileClasses();
}
/**
* compiles all .java files in /WEB-INF/lucee/classes via the ECJ BatchCompiler
* lucee code added to classpath via the jars in System classpath and the latest rc patch
*/
function CompileClasses() {
var java = {
System : createObject( 'java', 'java.lang.System' )
, PrintWriter : createObject( 'java', 'java.io.PrintWriter' )
, StringWriter : createObject( 'java', 'java.io.StringWriter' )
, BatchCompiler : createObject( 'java', 'org.eclipse.jdt.core.compiler.batch.BatchCompiler', 'ecj-4.2.2.jar' )
};
var src = expandPath( '' );
var rc = arrayLast( directoryList( expandPath( '{lucee-server}/../patches' ) ) );
var cp = java.System.getProperty( "java.class.path" ); // all libs from System classpath
cp &= Server.separator.path & rc; // add the lucee-Core to classpath
// writeDump(cp);
// abort;
var out = java.StringWriter.init();
var outWriter = java.PrintWriter.init( out, true );
var cmd = "-cp #cp# #src#";
outWriter.println( "Compiler Command: " & cmd );
java.BatchCompiler.compile( cmd, outWriter, outWriter, javaCast( 'null', '' ) );
outWriter.println( "Done." );
var result = out.getBuffer().toString().trim();
writeDump(result);
return result;
}
}
```
This method was found from: https://issues.jboss.org/browse/RAILO-2398