JAVA线程本地变量ThreadLocal和私有变量的区别

public class ThreadLocalExample {

    public static class MyRunnable implements Runnable {

        private ThreadLocal<Integer> threadLocal =

        new ThreadLocal<Integer>();
        int local = 0;

        @Override
        public void run() {

            threadLocal.set((int) (Math.random() * 100D));
            local = (int) (Math.random() * 100D);

            try {

                Thread.sleep(2000);

            } catch (InterruptedException e) {

            }

            System.out.println("threadLocal:" +threadLocal.get());
            System.out.println("local:" +local);

        }

    }

    public static void main(String[] args) {

        MyRunnable sharedRunnableInstance = new MyRunnable();

        Thread thread1 = new Thread(sharedRunnableInstance);

        Thread thread2 = new Thread(sharedRunnableInstance);

        thread1.start();

        thread2.start();

        try {
            thread1.join();
            thread2.join(); 
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } // wait for thread 1 to terminate

        // wait for thread 2 to terminate

    }

}