单例设计静态内部类

public class InnerclassSingleton {
    private InnerclassSingleton() {};

    private static class Singleton {
        private static final InnerclassSingleton i = new InnerclassSingleton();
    }

    public static InnerclassSingleton getInstance() {
        return Singleton.i;
    }
}

package com.example.SpringBootTest1.shejimoshi.singleton;
public class Test {
    public static void main(String[] args) {
        new Thread(() -> {
            InnerclassSingleton instance1 = InnerclassSingleton.getInstance();
            // com.example.SpringBootTest1.shejimoshi.singleton.InnerclassSingleton@6cb47364
            System.out.println(instance1);
        }).start();

        new Thread(() -> {
            InnerclassSingleton instance2 = InnerclassSingleton.getInstance();
            // com.example.SpringBootTest1.shejimoshi.singleton.InnerclassSingleton@6cb47364
            System.out.println(instance2);
        }).start();
    }
}