線程池：

int count = 200000;        long startTime = System.currentTimeMillis();        final List<Integer> l = new LinkedList<Integer>();        ThreadPoolExecutor tp = new ThreadPoolExecutor(1, 1, 60, TimeUnit.SECONDS, new LinkedBlockingDeque<Runnable>(count));        final Random random = new Random();        for (int i = 0; i < count; i++) {            tp.execute(new Runnable() {                                @Override                public void run() {                    l.add(random.nextInt());                }            });        }        tp.shutdown();        try {            tp.awaitTermination(1, TimeUnit.DAYS);        } catch (InterruptedException e) {            e.PRintStackTrace();        }        System.out.println(System.currentTimeMillis() - startTime);        System.out.println(l.size());

輸出結果：

1 1722 200000

線程：

int count = 200000;        long startTime = System.currentTimeMillis();        final List<Integer> l = new LinkedList<Integer>();        final Random random = new Random();        for (int i = 0; i < count; i++) {            Thread thread = new Thread(){                @Override                public void run(){                    l.add(random.nextInt());                }            };            thread.start();            try {                thread.join();            } catch (InterruptedException e) {                e.printStackTrace();            }        }        System.out.println(System.currentTimeMillis() - startTime);        System.out.println(l.size());

輸出結果：

1 335562 200000

總結：差異在于線程池是復用線程的，而不使用線程池是每次都要去創建線程。線程中執行工作很簡單，創建線程的開銷占整個時間的比例較大。