编译过后显示错误：找不到符号

求各位大神帮帮忙。
我的编码是这样的:
//filename:App9_8.java
class Student
{
private double weight;
private int high;
String sex;
public Student() //定义无参数的构造方法
{
weight=45;
high=160;
sex="女";
}
public Student(double w,int h,String str) //定义有三个参数的构造方法
{
weight=w;
high=h;
sex=str;
}
public void setSex()
{
System.out.println("该同学的性别为:"+sex);
}
double area()
{
return high*high;
}
double volume()
{
return area()*weight;
}
}
//import java.util.App9_8
public class App9_8
{
public static void main(String[] args)
{
Student volu1=new Student();
System.out.println("学生1的体重="+volu1.area());
System.out.println("学生1的高="+volu1.volume());
volu1.setStudent();
Student volu2=new Student(46,160,"女");
System.out.println("学生2的体重="+volu2.area());
System.out.println("学生2的高="+volu2.volume());
volu2.setStudent();
}
}
编译过后，显示：错误：找不到符号
volu1.setStudent();
符号：方法setStudent()
位置：类型为Student的变量volu1
错误：找不到符号
volu2.setStudent();
符号：方法setStudent()
位置：类型为Student的变量volu2

代码是多余的吧，删掉就好了。

class Student
{
    private double weight;
    private int high;
    String sex;
    public Student() //定义无参数的构造方法
    {
        weight=45;
        high=160;
        sex="女";
    }
    public Student(double w,int h,String str) //定义有三个参数的构造方法
    {
        weight=w;
        high=h;
        sex=str;
    }
    public void setSex()
    {
        System.out.println("该同学的性别为:"+sex);
    }
    double area()
    {
        return weight;
    }
    double volume()
    {
        return high;
    }
}
//import java.util.App9_8
public class App9_8
{
    public static void main(String[] args)
    {
        Student volu1=new Student();
        System.out.println("学生1的体重="+volu1.area());
        System.out.println("学生1的高="+volu1.volume());
        volu1.setSex();
        Student volu2=new Student(46,160,"女");
        System.out.println("学生2的体重="+volu2.area());
        System.out.println("学生2的高="+volu2.volume());
        volu2.setSex();
    }
}

类里面没有setStudent函数啊，你得在类里面增加setStudent函数

确实没有setStudent()方法啊，setSex()？