有类的定义大致如下:public class Student{String name;String sex;int age;public Student(String name, int age){ this.name = name; this.sex = "male"; this.age = age; } public Student(String name, String sex, int age){ this.name = name; this.sex = sex; this.age = age; } public Student(){ this("zhangsan", 20); }} 执行Student s = new Student()后,学生信息为