很纠结的一个问题。。。

Question

现在有两个包，下面的是第一包，在第二个包里看不到GraduateStudent类...package com.neusoft.vo;
     public class Student {
     public String name;
     public String sex;
     public int age;
     public String schoolName;     public  Student (){}
     public  Student(String name,String sex,int age,String schoolName){
      this.name=name;
      this.sex=sex;
      this.age=age;
      this.schoolName=schoolName;
      }     class GraduateStudent extends  Student {
     String specialityl;
     String teacher;
   
      public GraduateStudent(){}
      public GraduateStudent(String name,String sex,int age,String schoolName,String specialityl,String teacher){
      super.name=name;
      super.sex=sex;
      super.age=age;
      super.schoolName=schoolName;
      this.specialityl=specialityl;
      this.teacher=teacher;
     }
package test;
import com.neusoft.vo.*;
public class TestStudentAndGraduateStudent extends Student {
public static void main(String[] args) {
        Student zhou[]=new Student[2];
        zhou[0]=new Student("赵大","男",19,"华南理工大学");
        //不知道下面这样写可不可以，是Student 的引用然后是GraduateStudent类型的数组。应该行的吧
        zhou[1]=new GraduateStudent("孙三","男",25,"华南师范大学","教育学","李四");总是显示GraduateStudent不可见把它修饰成public 的话，Student类又看不到了
折磨了很久都不懂。。
刚学啊。。很多都不懂。。请大牛们解答

Answer 1

本帖最后由 AWUSOFT 于 2012-04-16 21:30:41 编辑

  

Answer 2

GraduateStudent是Student类的内部类，你把这两个类分别放在两个文件中（还在同一个包里）试试

Answer 3

把它写成两个类package com.neusoft.vo;
     public class Student {
     public String name;
     public String sex;
     public int age;
     public String schoolName;     public  Student (){}
     public  Student(String name,String sex,int age,String schoolName){
         this.name=name;
         this.sex=sex;
         this.age=age;
         this.schoolName=schoolName;
      }
package com.neusoft.vo;
     public class GraduateStudent extends  Student {
        String specialityl;
        String teacher;
   
      public GraduateStudent(){}
      public GraduateStudent(String name,String sex,int age,String schoolName,String specialityl,String teacher){
             super.name=name;
             super.sex=sex;
             super.age=age;
             super.schoolName=schoolName;
             this.specialityl=specialityl;
             this.teacher=teacher;
        }

Answer 4

不好意思。。好像我打漏了一个括号，不是内部类的吧。我是分开写的。我贴完整代码出来。。麻烦了
我把它们分成两个文件，还是不行呢在GraduateStudent还是不可见。。package com.neusoft.vo;
     public class Student {
     public String name;
     public String sex;
     public int age;
     public String schoolName;     public  Student (){}
     public  Student(String name,String sex,int age,String schoolName){
         this.name=name;
         this.sex=sex;
         this.age=age;
         this.schoolName=schoolName;
      }
     }
 
package com.neusoft.vo;
     public class GraduateStudent extends  Student {
       public  String specialityl;
       public String teacher;
   
      public GraduateStudent(){}
      public GraduateStudent(String name,String sex,int age,String schoolName,String specialityl,String teacher){
             super.name=name;
             super.sex=sex;
             super.age=age;
             super.schoolName=schoolName;
             this.specialityl=specialityl;
             this.teacher=teacher;
        }
     }
另外的一个包，在这里调用不了GraduateStudent
package test;
import com.neusoft.vo.*;
public class TestStudentAndGraduateStudent   {
public static void main(String[] args) {
        Student zhou[]=new Student[6];
        zhou[0]=new Student("赵大","男",19,"华南理工大学");
        zhou[1]=new Student("钱二","男",17,"中山大学");
        //这里报错，总是显示GraduateStudent不可见。
        zhou[2]=new GraduateStudent("孙三","男",25,"华南师范大学","教育学","李四");
        zhou[3]=new Student("周五","女",18,"东软学院");
        zhou[4]=new GraduateStudent("吴六","女",24,"清华大学","工商企业管理","郑七");
        zhou[5]=new Student("罗八","男",18,"佛山科技大学");
        
        // 找出其中女的信息然后修改。
        for(int i=0;i<zhou.length;i++){
         if(zhou[i].sex.equals("女")){
         zhou[i].schoolName="广东工业大学";  
         }
        }
        
        // 输出学生的信息。
        for(int i=0;i<zhou.length;i++){
         System.out.println("姓名："+zhou[i].name+"\n"+"性别："+zhou[i].sex+"\n"+"年龄："+zhou[i].age+"\n"+"学校："+zhou[i].schoolName+"\n"+"专业："
                      +zhou[i].specialityl+"\n"+"导师："+zhou[i].teacher);
        }

}}代码有点乱，不好意思了

Answer 5

不可能吧，但是            System.out.println("姓名："+zhou[i].name+"\n"+"性别："+zhou[i].sex+"\n"+"年龄："+zhou[i].age+"\n"+"学校："+zhou[i].schoolName+"\n"+"专业："
                                 +zhou[i].specialityl+"\n"+"导师："+zhou[i].teacher);这里肯定要报错的，因为Student里面没有specialityl和teacher这两个属性。

Answer 6

if(zhou[i] instanceof GraduateStudent){
    GraduateStudent gs = (GraduateStudent)zhou[i];
}
这样强制转换成GraduateStudent，然后再获取