题解 | #创建单例对象#

public class Main {

    public static void main(String[] args) {
        Singleton s1 = Singleton.getInstance();
        Singleton s2 = Singleton.getInstance();
        System.out.println(s1 == s2);
    }

}

class Singleton {

    private static Singleton instance;

    private Singleton() {

    }
    public static Singleton getInstance() {
        if (instance == null) {
            instance = new Singleton();
        }
        return instance;
    }
}