单例模式饿汉式

单例模式
饿汉式：类一加载就创建对象

public class Student {
    private Student() {
    }

    //静态随着类的加载而加载，所以叫做饿汉式
    private static Student s = new Student();

    public static Student GetStudent() {
        return s;
    }
}

public class StudentDemo {
    public static void main(String[] args) {
        Student s1=Student.GetStudent();

        Student s2=Student.GetStudent();

        System.out.println(s1==s2);//true
    }
}