classPerson{String name;int age;int grade;Person(){System.out.println("Person的无参数构造函数");}Person(String name ,int age){this.name = name;this.age = age;System.out.println("Person的有参数构造函数");}void eat(){System.out.println("吃饭");}}classStudent extends Person{//在子类的构造函数当中，必须调用父类的构造函数Student(){ super();System.out.println("student的无参数构造函数");}Student(String name,int age,int grade){//this.name = name;//this.age = age; super(name,age);this.grade = grade;}}classTest{publicstaticvoid main(String args []){Student student =newStudent("zhagnsan",18,3);System.out.println(student.name);System.out.println(student.age);System.out.println(student.grade);}}原文：http://www.cnblogs.com/arroneve/p/5815434.html