Avoid printing the last comma

Question

I\'m trying to print this loop without the last comma. I\'ve been Googling about this and from what i\'ve seen everything seems overcomplex for such a small problem. Surely

Answer 1

I might get stoned to death for this answer

public static void atob(int a,int b) {
  if(a<=b) {
    System.out.println(a);
      for(int i = a+1;i<=b;i++) {
        System.out.println(","+i);
      }
    }
  }
}  

Answer 2

Use StringBuilder for it. use substring based index.

public class arraySort {
    public static void main(String[] args) {
        int a[] = { 2, 7, 5, 6, 9, 8, 4, 3, 1 };
        for (int i = 0; i < a.length; i++) {
            for (int j = i + 1; j < a.length; j++) {
                if (a[i] < a[j]) {
                    int temp;
                    temp = a[i];
                    a[i] = a[j];
                    a[j] = temp;
                }
            }
        }

        System.out.print("Descending order:{");
        StringBuilder br = new StringBuilder();
        for (int i = 0; i < a.length; i++) {
            br.append(a[i] + ",");
        }
        System.out.print( br.substring(0, br.length()-1));
        System.out.println("}");

    }

}

Answer 3

Clunky solution, but hey - it works.

public static void atob(int a, int b){
 int count = 1;
  for(int i = a; i <= + b; i++) {
       System.out.print(i);
       if(count!=((b + 1) - a)) {
         System.out.print(", ");
         count++;
       }
    }
}

Alternatively, this works too.

public static void atob(int a, int b){
 int count = 0;
  for(int i = a; i <= + b; i++) {
    if(count > 0){
      System.out.print(", ");
    }
       System.out.print(i);
      count++;
   }
}

Answer 4

Found another simple way using regex:

String str = "abc, xyz, 123, ";
str = str.replaceAll(", $", "");
System.out.println(str);  // "abc, xyz, 123"

Answer 5

You can simply use escape sequence for backspace(\b),outside the main loop,it will delete the last comma.

public static void atob(int a,int b)
        {
            for(int i = a; i <= + b; i++) 
            {
                    System.out.print(i + ",");
            }
            System.out.print("\b");
        }

Answer 6

A general approach could be to make a distinction between the first item and all the others. The first run, no comma is printed BEFORE i. After that, a comma is printed before i, every time.

public static void atob(int a,int b) {
    boolean first = true;
    for(int i = a; i <= + b; i++) {
        if ( first == false ) System.out.print(","); 
        System.out.print(i);
        first = false;
    }
}

In this specific case, using the ternary operator (http://en.wikipedia.org/wiki/Ternary_operation), you could write it as compact as:

public static void atob(int a,int b) {
    for(int i = a; i <= + b; i++) {
        System.out.print( i + ( i < b ? "," : "" ) ); 
    }
}

Without ternary operation, this would look like this (and is more readable, which is often a good thing):

public static void atob(int a,int b) {
    for(int i = a; i <= + b; i++) {
        System.out.print( i ); 
        if ( i < b ) System.out.print( "," );
    }
}

(note that + b is the same as b, so you could replace that, as others have done in their answers)