constructors

[khamuruddeen]

class student
{
String name;
String dep;
int no;

public student(String fn,String de,int n)
{
name=fn;
dep=de;
no=n;
display();
}
public student()
{

}
public void changedep(String dep)
{
this.dep=dep;
System.out.println("dep of student is changed to "+dep);
display();
}
public void display()
{
System.out.println("Name: "+name);
System.out.println("Department: "+dep);
System.out.println("Number: "+no);
}
}

public class cla extends student
{
int nostu=0;
public void joinstu(String n1,String d1,int no1)
{
student st=new student(n1,d1,no1);
nostu++;
System.out.print("The new Student "+n1);System.out.print(" with no"+no1);System.out.print("is addeed to"+d1);System.out.print("departmenet in the class");
}
public void nostud()
{
System.out.println("No of students is "+nostu);
}
public static void main(String args[])
{
joinstu("kami","ece",39);
nostud();
changedep("cse");
}
}







its my program iam coming errors are




D:\java>javac cla.java
cla.java:47: non-static method joinstu(java.lang.String,java.lang.String,int) ca
nnot be referenced from a static context
joinstu("kami","ece",39);
^
cla.java:48: non-static method nostud() cannot be referenced from a static conte
xt
nostud();
^
cla.java:49: non-static method changedep(java.lang.String) cannot be referenced
from a static context
changedep("cse");
^
3 errors

D:\java>



then what i hav 2 do pls advice

[hardwired]

public class StudExtension extends Student
{
    int nostu=0;

    public void joinstu(String n1,String d1,int no1)
    { 
        Student st=new Student(n1,d1,no1);
        nostu++;
        System.out.print("The new Student "+n1);
        System.out.print(" with no"+no1);
        System.out.print("is addeed to"+d1);
        System.out.print("departmenet in the class");
    }
 
    public void nostud()
    {
        System.out.println("No of students is "+nostu);
    }

    public static void main(String[] args)
    {
        StudExtension se = new StudExtension();
        se.joinstu("kami","ece",39);
        se.nostud();
        se.changedep("cse"); 
    }
}

class Student
{
    ...

    public Student()
    {
        this(null, null, 0);
    }

[khamuruddeen]

thank u for ur suggestion sir..;