public void doParallel(Runnable... runnables) {
    List<Thread> threads = new ArrayList<>();
    Arrays.asList(runnables).forEach(runnable -> threads.add(new Thread(runnable)));
    threads.forEach(thread -> thread.start());
    threads.forEach(thread -> { try { thread.join(); } catch (InterruptedException e) {}});
}
doParallel(
    () -> doSomething(),
    () -> doSomething(),
    () -> doSomething()
);