Compiling Java code from string results in ClassNotFoundException -


i'm trying code example uses javax.tools compile code in string. class.forname results in classnotfoundexception. know why? i'm using java 7.

        import java.io.ioexception;         import java.io.printwriter;         import java.io.stringwriter;         import java.lang.reflect.invocationtargetexception;         import java.net.uri;         import java.util.arraylist;         import java.util.arrays;         import java.util.list;          import javax.tools.diagnostic;         import javax.tools.diagnosticcollector;         import javax.tools.javacompiler;         import javax.tools.javafileobject;         import javax.tools.simplejavafileobject;         import javax.tools.toolprovider;         import javax.tools.javacompiler.compilationtask;           public class main {             public static void main(string args[]) throws ioexception {                 javacompiler compiler = toolprovider.getsystemjavacompiler();                 diagnosticcollector<javafileobject> diagnostics = new diagnosticcollector<javafileobject>();                  stringwriter writer = new stringwriter();                 printwriter out = new printwriter(writer);                 out.println("public class helloworld {");                 out.println("  public static void main(string args[]) {");                 out.println("    system.out.println(\"this in java file\");");                 out.println("  }");                 out.println("}");                 out.close();                 javafileobject file = new javasourcefromstring("helloworld", writer.tostring());                  iterable<? extends javafileobject> compilationunits = arrays.aslist(file);                 compilationtask task = compiler.gettask(null, null, diagnostics, optionlist, null, compilationunits);                  boolean success = task.call();                 (diagnostic diagnostic : diagnostics.getdiagnostics()) {                     system.out.println(diagnostic.getcode());                     system.out.println(diagnostic.getkind());                     system.out.println(diagnostic.getposition());                     system.out.println(diagnostic.getstartposition());                     system.out.println(diagnostic.getendposition());                     system.out.println(diagnostic.getsource());                     system.out.println(diagnostic.getmessage(null));                  }                 system.out.println("success: " + success);                  if (success) {                     try {                         class.forname("helloworld").getdeclaredmethod("main", new class[] { string[].class })                                 .invoke(null, new object[] { null });                     } catch (classnotfoundexception e) {                         system.err.println("class not found: " + e);                     } catch (nosuchmethodexception e) {                         system.err.println("no such method: " + e);                     } catch (illegalaccessexception e) {                         system.err.println("illegal access: " + e);                     } catch (invocationtargetexception e) {                         system.err.println("invocation target: " + e);                     }                 }             }         }          class javasourcefromstring extends simplejavafileobject {             final string code;              javasourcefromstring(string name, string code) {                 super(uri.create("string:///" + name.replace('.','/') + kind.source.extension), kind.source);                 this.code = code;                                                                           }              @override             public charsequence getcharcontent(boolean ignoreencodingerrors) {                 return code;             }         }

the classloader has no idea of helloworld class. can this:

urlclassloader classloader = urlclassloader.newinstance(new url[] { root.touri().tourl() }); //root path class file class<?> cls = class.forname("helloworld", true, classloader);

you can see a full example here.


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