请高人指点新手JAVA问题，在线等。

package test;
public class Test8 {
public static void main(String[] args) {
Student s1=new Student("李梅","20110102",19,'女');
s1.show();
/*Student s2=new Student("张强","20110103",19,'男');
s2.show();
Student s3=new Student("芳芳","20110104");
s3.show();*/
}
}
class Student{
private String name;
private String number;
private int age;
private char sex;
Student(){

}
Student(String sname,String snumber){
name=sname;
number=snumber;
}
Student(String sname,String snumber,int sage){
this(sname,snumber);
age=sage;
}
Student(String sname,String snumber,int sage,char ssex){
this(sname,snumber,sage);
sex=ssex;
}
void show(){
System.out.println("姓名："+name+" ");
System.out.println("学号："+number+" ");
System.out.println("年龄："+age+" ");
System.out.println("性别："+sex+" ");
}
}

错误提示：
Exception in thread "main" java.lang.NoSuchMethodError: test.Student.<init>(Ljava/lang/String;Ljava/lang/String;IC)V
at test.Test8.main(Test8.java:4)