JavaCompiler.java

public static List<CompilerOutput> compile(String className, String code) {
        try {
            JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
            DiagnosticCollector<JavaFileObject> ds = new DiagnosticCollector<>();

            try (StandardJavaFileManager mgr = compiler.getStandardFileManager(ds, null, null)) {

                JavaFileObject file = new InMemoryJavaCode(className, code);
                Iterable<? extends JavaFileObject> sources = Arrays.asList(file);

                CompilationTask task = compiler.getTask(null, mgr, ds, null, null, sources);
                task.call();
            }

            return ds.getDiagnostics().stream()
                    .map(InMemoryJavaCompiler::toCompilerOutput)
                    .collect(toList());
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }
    }