Thread: Calling constructor error

Hi i'm trying to call super constructor but found the error :call to super must be first statement in constructor.

This is my code in parent class (NO ERRORS)
import java.util.Date;
public abstract class GreetingCard implements Comparable {
String message;
Date arrivalDate;

void greetingCard(String m, Date d){
this.message = m;
this.arrivalDate = d;
}

public int comPareTo(GreetingCard other){
if(arrivalDate.equals(other.arrivalDate)){
return 0;
}
else{
if(arrivalDate.equals(other.arrivalDate)){
return 1;
}
else{
return -1;
}
}
}

abstract String formatMessage();
}

This is my code in extends class (ERRORS)
import java.util.Date;
public class BirthdayCard extends GreetingCard {
String message;
Date arrivalDate;

void BirthdayCard(String bm, Date dd){
super(bm,dd);
this.message = bm;
this.arrivalDate = dd;
}

String formatMessage(){
return ("Happy Birthday" + this.message);
}

}

Pls...pls help me...

The compiler is telling you that you're trying to call a super constructor that doesn't exist, and the compiler is (as usual) in fact correct. Remember that constructors must be named *exactly* the same as the class their in, both spelling and capitalization, and constructors return nothing, no void, no nothing.

so if i change my code in parent class to just greetingCard(String m, Date d){} i'm getting error now in my parent class. SO how should i write the code in?

Re-read my post and then look carefully at the line that contains the error and it will become apparent. Remember that the Java compiler is unforgiving.

ok got it thanks...the compiler is unforgiving...

--- Update ---

ok now i have this error :BirthdayCard is not abstract and does not override abstract method compareTo(object) in comparable...

It's essentially the same problem. Again check spelling. Again check capitalization. This sort of thing should be automatic now when you receive these types of errors. You shouldn't need our help for similar issues.

I'm still getting this same error messages. Sorry this is my first try doing object oriented programming
I did re-check my spelling and caps everything seems to be fine to me. Cud u pls check for me?

Please show your latest code attempt *with code tags* and in particular your compareTo method, the one that the compiler says is missing. And since that's the method the compiler complains about, again that's the method signature that you should check most carefully, again including capitalization.

This is parent class
import java.util.Date;
public abstract class GreetingCard implements Comparable {
String message;
Date arrivalDate;

GreetingCard(String message, Date arrivalDate){
this.message = message;
this.arrivalDate = arrivalDate;
}

public int comPareTo(GreetingCard other){
if(arrivalDate.equals(other.arrivalDate)){
return 0;
}
else{
if(arrivalDate.equals(other.arrivalDate)){
return 1;
}
else{
return -1;
}
}
}

abstract String formatMessage();
}

import java.util.Date;
public class BirthdayCard extends GreetingCard{ <---BirthdayCard is not abstract and does not override abstract method compareTo(Object) in Comparable
----
(Alt-Enter shows hints)

BirthdayCard(String bm, Date dd){
super(bm,dd);
this.message = bm;
this.arrivalDate = dd;
}
public Date arrivalDate(){
return arrivalDate;
}
String formatMessage(){
return ("Happy Birthday" + this.message);
}
}

import java.util.Date;
public class Anniversary extends GreetingCard { <---Anniversary is not abstract and does not override abstract method compareTo(Object) in Comparable
----
(Alt-Enter shows hints)
String occassion;

Anniversary(String am,Date ad){
super(am,ad);
this.message = am;
this.arrivalDate = ad;
}

String formatMessage(){
return("Happy "+occassion+"Anniversary "+message);
}

}

I have 1 more class, ECardSeller which i have not start due to stuck bcos of these errors. And another class CarPrinter which is from another different package.

Spelling and capitalization matters, check to see if your code correctly overrides the abstract method public int compareTo(GreetingCard other); .

ok so i know i have to override the abstract method compareTo, but how should i code it in my other extends class?I am a beginner for object oriented programming so pls guide me huhu

How do i post in code tags?

[/code]
import java.util.Date;
public abstract class GreetingCard implements Comparable {
String message;
Date arrivalDate;

GreetingCard(String message, Date arrivalDate){
this.message = message;
this.arrivalDate = arrivalDate;
}

public int comPareTo(GreetingCard other){
if(arrivalDate.equals(other.arrivalDate)){
return 0;
}
else{
if(arrivalDate.equals(other.arrivalDate)){
return 1;
}
else{
return -1;
}
}
}

abstract String formatMessage();
}

import java.util.Date;
public class BirthdayCard extends GreetingCard{

BirthdayCard(String bm, Date dd){
super(bm,dd);
this.message = bm;
this.arrivalDate = dd;
}
public Date arrivalDate(){
return arrivalDate;
}
String formatMessage(){
return ("Happy Birthday" + this.message);
}
}

import java.util.Date;
public class Anniversary extends GreetingCard {
String occassion;

Anniversary(String am,Date ad){
super(am,ad);
this.message = am;
this.arrivalDate = ad;
}

String formatMessage(){
return("Happy "+occassion+"Anniversary "+message);
}

}

import java.util.Date;
public abstract class GreetingCard implements Comparable {
    String message;
    Date arrivalDate;
 
    GreetingCard(String message, Date arrivalDate){
        this.message = message;
        this.arrivalDate = arrivalDate;
    }
 
    public int comPareTo(GreetingCard other){
        if(arrivalDate.equals(other.arrivalDate)){
            return 0;
        }
        else{
            if(arrivalDate.equals(other.arrivalDate)){
                return 1;
            }
            else{
                return -1;
            }
        }
    }
 
    abstract String formatMessage();
}
import java.util.Date;
public class BirthdayCard extends GreetingCard{
 
    BirthdayCard(String bm, Date dd){
        super(bm,dd);
        this.message = bm;
        this.arrivalDate = dd;
    }
    public Date arrivalDate(){
        return arrivalDate;
    }
    String formatMessage(){
        return ("Happy Birthday" + this.message);
    }
}
import java.util.Date;
public class Anniversary extends GreetingCard {
    String occassion;
 
    Anniversary(String am,Date ad){
        super(am,ad);
        this.message = am;
        this.arrivalDate = ad;
    }
 
    String formatMessage(){
        return("Happy "+occassion+"Anniversary "+message);
    }
 
}

which spelling do i need to correct and from which class??

Originally Posted by haliza hadi

which spelling do i need to correct and from which class??

The compiler is telling you exactly what needs to be fixed.

Again, the compiler is extremely picky, and so you must be just as picky when you create your programs. Your errors are simply from being careless, and we can't teach you to be careful, but instead you must learn this yourself by being constantly vigilant.

I suggest that if you can't use an IDE such as Eclipse or NetBeans, that you compile frequently when creating programs, that you add code to your programs one to lines at a time, and that each time you follow this with a compilation. If the code doesn't compile, then don't add *any* new lines until you've fixed the compilation errors present.

ok..i've found the spelling for method "compareTo"

I try to work out the error in my child class but to no avail...what does this error mean??
BirthdayCard is not abstract and does not override abstract method compareTo(Object) in Comparable
----

Did you correct the spelling for the compareTo method? Can you please post the current code that you have in the Code tags?

Yes i did change the spelling for compareTo

 
import java.util.Date;
public abstract class GreetingCard implements Comparable {
    String message;
    Date arrivalDate;
 
    GreetingCard(String message, Date arrivalDate){
        this.message = message;
        this.arrivalDate = arrivalDate;
    }
 
    public int compareTo(GreetingCard other){
        if(arrivalDate.equals(other.arrivalDate)){
            return 0;
        }
        else{
            if(arrivalDate.equals(other.arrivalDate)){
                return 1;
            }
            else{
                return -1;
            }
        }
    }
 
    abstract String formatMessage();
}
import java.util.Date;
public class BirthdayCard extends GreetingCard{
 
    BirthdayCard(String bm, Date dd){
        super(bm,dd);
        this.message = bm;
        this.arrivalDate = dd;
    }
    public Date arrivalDate(){
        return arrivalDate;
    }
    String formatMessage(){
        return ("Happy Birthday" + this.message);
    }
 
}
 
import java.util.Date;
public class Anniversary extends GreetingCard {
    String occassion;
 
    Anniversary(String am,Date ad){
        super(am,ad);
        this.message = am;
        this.arrivalDate = ad;
    }
 
    String formatMessage(){
        return("Happy "+occassion+"Anniversary "+message);
    }
 
}

--- Update ---

Yes i did change the spelling for compareTo

 
import java.util.Date;
public abstract class GreetingCard implements Comparable {
    String message;
    Date arrivalDate;
 
    GreetingCard(String message, Date arrivalDate){
        this.message = message;
        this.arrivalDate = arrivalDate;
    }
 
    public int compareTo(GreetingCard other){
        if(arrivalDate.equals(other.arrivalDate)){
            return 0;
        }
        else{
            if(arrivalDate.equals(other.arrivalDate)){
                return 1;
            }
            else{
                return -1;
            }
        }
    }
 
    abstract String formatMessage();
}
import java.util.Date;
public class BirthdayCard extends GreetingCard{
 
    BirthdayCard(String bm, Date dd){
        super(bm,dd);
        this.message = bm;
        this.arrivalDate = dd;
    }
    public Date arrivalDate(){
        return arrivalDate;
    }
    String formatMessage(){
        return ("Happy Birthday" + this.message);
    }
 
}
 
import java.util.Date;
public class Anniversary extends GreetingCard {
    String occassion;
 
    Anniversary(String am,Date ad){
        super(am,ad);
        this.message = am;
        this.arrivalDate = ad;
    }
 
    String formatMessage(){
        return("Happy "+occassion+"Anniversary "+message);
    }
 
}

Again the compiler is telling you exactly what is wrong. It's saying that compareTo must accept an Object parameter, while you've written it to accept a GreetingCard parameter. You can do one of two things:

1. Either change your compareTo method to one that accepts an Object parameter. If you do this, then inside the method you'll have to assign the parameter into a GreetingCard variable and will need to cast it to GreetingCard to do this.
2. Or have your class implement the generic version of the interface, Comparable<GreetingCard>.

Regardless, remember that the compiler error messages are usually very helpful in figuring out a problem and in solving it.