单例的一种写法

private static VIPTest vipTest = null;
	protected static ArrayList orgList = null;
	
	private VIPTest() {
	}
	public static VIPTest getInstance() {
		if (null == vipTest) {
			synchronized (VIPTest.class) {
				if (null == vipTest) {
					vipTest = new VIPTest();
					
				}
			}
		}
		return vipTest;
	}