what's wrong with the for-each

[Bin Qian]

Hello everyone:
here is the code

    import java.util.Scanner;
 
class WrongNException extends Exception{
    WrongNException(){
        super("N must be positive");
     }
}
 
public class AverageCount{
   private int sumOfNumber;
   private int[] number;
 
   AverageCount(){
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Please input the sum of the number that you want to count:");
        sumOfNumber = keyboard.nextInt();
        try{
         if(sumOfNumber <= 0) throw new WrongNException();
        }catch(WrongNException e){ e.getMessage();}
        number = new int[sumOfNumber];
        System.out.println("Please input the " + sumOfNumber + " number that you want to count:");
// (1)       for(int i=0;i<number.length;i++){
//            number[i] = keyboard.nextInt();
//            }
 
// (2)       for(int nb : number){
//            nb = keyboard.nextInt();
//            }
        for(int nb : number){
            System.out.println(nb);
         }
    }
 
   private float count(int[] a){
        int sum = 0;
        for(int nb : a){
            sum = sum + nb; 
            System.out.println(sum);
         }
        return sum/a.length;
    } 
 
   public static void main(String[] args){
        AverageCount one = new AverageCount();
        System.out.println("The average of the "+ one.sumOfNumber +" numbers is " + one.count(one.number)); 
    }
}

the program calculates the average of sumOfNumber(a variable in the program) integers, and the sumOfNumber is enterd by users also the number;
when i use comment(1) it's ok,but it doesn't work when i use commnet(2), why???

[Paul Sturrock]

By "doesn't work" do you mean doesn't compile? If so, check the version of Java you are using; the for : each syntax is only available from v5.0 up.

If by "doesn't work" you mean something else, can you lease explain what that is (by describing the behaviour and/or posting any stack trace you have)?

[Anton Uwe]

The foreach-loop (as in //(2)) is equivalent to

for (int i = 0; i < number.length; i++) {
    int nb = number[i];
    nb= keyboard.nextInt();
}

There is no "reassignment" like "number[i]=nb".

[Bin Qian]

ok !thank you everyone espatically Anton Uwe!
i see now!