懒汉式单例类

public class LazySingleton {
    private static LazySingleton instance = null;

    private LazySingleton() {
    }

    synchronized public static LazySingleton getInstance() {
        if (instance == null) {
            return new LazySingleton();
        } else {
            return instance;
        }
    }

    public void test() {
        System.out.println("懒汉式实例");
    }

}

public class SingletonTest {
    public static void main(String[] args) {
        LazySingleton ls = LazySingleton.getInstance();
        ls.test();
        LazySingleton ls2 = LazySingleton.getInstance();
        ls2.test();

        //懒加载,刚开始没有,后来创建了,所以不一样
        System.out.println(ls==ls2);
    }
}

懒汉式实例
懒汉式实例
false