單例模式比較懶漢模式的優化代碼

public class Singleton1 {

private static Singleton1 instance = null;

private Singleton1() {
}

public static Singleton1 getInstances() throws InterruptedException {
	if (instance == null) { //爲了優化，當instance不爲空是，直接返回實例對象
		
		synchronized (Singleton1.class) { 
			if (instance == null) {
				Thread.sleep(100);
				instance = new Singleton1();
			}
			return instance;
		}
	}
	return instance;
}

}