这不是一个ABA问题，哈哈

ABA.java

public class ABA {
	private static int count = 0;
	public static void main(String[] args) throws Exception {
		ABA aba = new ABA();
		aba.increase();
		Thread.sleep(10000);
		System.out.println(count);
	}

	public void increase() {
		for(int i=0; i<1000; i++) {
			Thread t = new Thread(new Runnable() {
				public void run() {
					try {
						Thread.sleep(10);
					} catch (InterruptedException e) {
					}
					//if not synchronized , count <= 1000
					synchronized(ABA.class) {
						count++;
					}
				}
			});
			t.start();
		}
	}
}