Java tutorial
import java.io.IOException; import java.io.PrintWriter; import java.io.StringWriter; import java.lang.reflect.InvocationTargetException; import java.net.URI; import java.util.Arrays; 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; import javax.tools.JavaFileObject.Kind; public class CompileSourceInMemory { 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 is in another 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, null, null, compilationUnits); boolean success = task.call(); for (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; } }