Thread: What is wrong with this code?

//m a rookie at java programming..plz tel me why this doesn't works

//Program to get input from user and find the average
//this program terminates after first iteration of DO,WHILE Loop


import java.util.Scanner;

public class Avi {
public static void main(String args[]){

int flag=0, no;
Scanner ip = new Scanner(System.in);
Scanner st = new Scanner(System.in);

do{
System.out.println("Enter no : ");
no = ip.nextInt();

System.out.println("Wanna enter more numbers?(y/n) : ");
String c = st.nextLine();

if(c=="y" || c=="Y")
flag+=1;
}while(flag<0);

}

//Method to calculate average
public static int average(int...numbers){
int total=0;
for(int x: numbers)
total+=x;
return total/numbers.length;
}

}

Hello there A19, welcome to JavaProgrammingForums.

When posting code, please learn to surround your code in tags, such as the ones found in my signature.

Your first issue is a very basic and common mistake, so if you take the time to quickly read the following article you will soon discover the problem.
http://www.javaprogrammingforums.com...-mistakes.html

Secondly, although it will pass into the while loop the first time, you should really be checking whether your 'flag' variable is less than OR equal to 0, and not only less than 0.

Can you post your updated code on here then? Wrapped in code tags of course.

I'm still not 100% awake yet but shouldn't the condition be while(flag > 0). If the user enters "y" to continue and you increment flag by 1 (assuming this gets fixed) then flag will be greater than zero so you can keep looping and allowing user to enter more numbers. Also what happens when user enters "n"?

It's true that (flag > 0) is just as, if not more viable than the alternative, but either way, there isn't much logic behind either approach with the current code.
Really, the only real issue here is the == operator vs .equals() method.

Originally Posted by newbie

the only real issue here is ....

No there are 3 issues and they are all very real.

1. The correct condition in the if statement
2. The correct condition in the loop
3. How to exit when user enters "n"

Just realised there is a 4th problem

4. The average is never calculated and displayed.

Even more

5. Wrong return type for the average method.

But you're thinking of the overall program.
A19 Came here asking why his program didn't work.

As the average() method is never called, it isn't part of the original issue A19 had.

5. Wrong return type for the average method.

Syntax is ok, therefore not a reason why his code "doesn't work".

What his program is supposed to do is irrespective of how it does it.

So your plan is to have OP fix one problem at a time and then when they encounter the next to come back here and post their code, ask some vague question (as most do) and then fix that one. Rinse and repeat until they have a complete program. Or you can explain to them all the problems with their code so they can work on fixing the entire program.

Essentially yes, there isn't much point in telling the OP to do this, that and the other before fixing the more underlying problems which take his program nowhere.
Obviously I realise it would then get repetitive, coming back and forth... but as the OP is obviously learning the basics, it's far better to chop the problem into smaller parts and deal with them one at a time.

Of course that approach isn't for everyone, but It's what I find to make the most sense for beginners, until they get better problem solving skills.

Each to his/her own. If I see problems in the code then I will alert the person to all of them rather wasting my time doing all this back and forth dealing with one issue at a time.

Originally Posted by higv2000

Couple of comments and solution:
1. If your intention is to continue the loop when the user enters "y" or "Y" for C, then you can replace the while loop as }while(c == 'y' || c == 'Y');

Since the variable c is a String that won't work.

2. Secondly, if you are doing String comparison, you should use .equals() method. What you are comparing is like memory addresses or simulation of pointers.

Already covered and solved.

3. I don't see any declaration for the variable "flag" although you don't need this anymore if you modify the while construct as explained above in #1.

Declared on the first line of the main method.

The problems continue.

6. Where do you store the values entered?