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 there is an easy solution to avoid printing the last comma. Much appreciated if somebody could help me out, this is driving me insane!!!

For example it loops from 1-10 // 1,2,3,4,5,6,7,8,9,10, < do not want this last comma

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

You could use a While loop instead... or perhaps put it all into a single string and then use substring of the length -1 — radimpe, Apr 03 '12 at 10:56
You could use some book http://stackoverflow.com/questions/1076580/recommend-an-algorithms-exercise-book — kommradHomer, Apr 03 '12 at 10:59
Forgot to mention...i have to loop using for because the teacher said so...definitely not in a good spot. — OMGjava, Apr 03 '12 at 11:01
@OMGjava mate i dont think sitting there and refreshing this page will serve the motivation of homework — kommradHomer, Apr 03 '12 at 11:25
possible duplicate of [A quick and easy way to join array elements with a separator (the oposite of split) in Java](http://stackoverflow.com/questions/1978933/a-quick-and-easy-way-to-join-array-elements-with-a-separator-the-oposite-of-spl) — a'r, Apr 03 '12 at 13:24

Aadi Droid · Answer 1 · 2017-04-14T14:21:24.737

13

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);
      }
    }
  }
}

edited Apr 14 '17 at 14:21

answered Apr 03 '12 at 10:56

Aadi Droid

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I don't see why, it's the way I'd do it. It just needs a range check for a prior to outputting a. – mcfinnigan Apr 03 '12 at 10:57

score 6 · Answer 2 · answered Apr 03 '12 at 12:46

Yet another way to do this.

String sep = "";
for(int i = a; i <= b; i++) {
    System.out.print(sep + i);
    sep = ",";
}

if you are using a StringBuilder

StringBuilder sb = new StringBuilder();
for(int i = a; i <= b; i++)
    sb.append(i).append(',');
System.out.println(sb.subString(0, sb.length()-1));

score 5 · Answer 3 · edited Apr 12 '17 at 22:45

5

Try this

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

edited Apr 12 '17 at 22:45

Pshemo

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answered Apr 03 '12 at 10:55

Farhan Ahmed

342
1
8

if A is greater than B then it still prints A. – Aadi Droid Apr 03 '12 at 11:01
This won't compile as the variable `i` is out of scope in the last print statement. – Alderath Apr 03 '12 at 11:20
Thanks for giving me perspective to this! – OMGjava Apr 03 '12 at 13:16

charlie · Answer 4 · 2017-07-14T14:45:46.263

Java 8:

IntStream.rangeClosed(a, b)
         .collect(Collectors.joining(","));

If you want to perform interleaving actions:

Java 8:

IntStream.rangeClosed(a, b)
         .peek(System.out::print)
         .limit(b - a) // [a:(b-1)]
         .forEach(i -> System.out.print(","));

Java 9:

IntStream.rangeClosed(a, b)
         .peek(System.out::print)
         .takeWhile(i -> i < b) // [a:(b-1)]
         .forEach(i -> System.out.print(","));

Reg · Answer 5 · 2012-04-03T12:30:32.953

3

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

When called with

atob(0,10);

Will give the output

0,1,2,3,4,5,6,7,8,9,10

edited Apr 03 '12 at 12:30

answered Apr 03 '12 at 11:08

Reg

10,717
6
37
54

atob(10,0) will give 10 as output, but should print nothing. – Jochem Apr 03 '12 at 11:14
Thanks for giving me perspective to this! – OMGjava Apr 03 '12 at 13:17

score 1 · Answer 6 · answered Apr 03 '12 at 11:13

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)

Thanks for giving me perspective to this! – OMGjava Apr 03 '12 at 13:17 — OMGjava, Apr 03 '12 at 13:17

score 0 · Answer 7 · answered Aug 04 '16 at 15:17

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("}");

    }

}

score 0 · Answer 8 · answered Jul 14 '17 at 14:56

0

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(",");
            }
        }
}

answered Jul 14 '17 at 14:56

Khaled Hossain

1
1

score 0 · Answer 9 · answered Jan 04 '18 at 15:29

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++;
   }
}

score 0 · Answer 10 · answered Mar 30 '18 at 17:59

0

Found another simple way using regex:

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

answered Mar 30 '18 at 17:59

sameer_v

414
4
11

score 0 · Answer 11 · answered Jun 16 '18 at 14:47

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");
        }

score 0 · Answer 12 · edited Apr 03 '12 at 13:36

0

Try:

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

    for (int i = a; i < b ; i ++ ) {
        System.out.print("," + i);
    }
}

edited Apr 03 '12 at 13:36

Mxyk

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answered Apr 03 '12 at 11:13

Anish Dasappan

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Thanks for giving me perspective to this! – OMGjava Apr 03 '12 at 13:17

score 0 · Answer 13 · answered Apr 03 '12 at 11:16

With slight adjustments (method name, variables, and space after comma):

public static void printSequence(int start, int end) {
  if (end < start) {
    return; // or however you want to handle this case
  }
  if (end == start) {
    System.out.print(start);
    return;
  }
  StringBuilder sequence = new StringBuilder();
  for (int i = start; i <= end; i++) {
    sequence.append(i).append(", ");
  }
  // now simply print the sequence without the last ", "
  System.out.print(sequence.substring(0, sequence.length() - 2));
}

Thanks for giving me perspective to this! – OMGjava Apr 03 '12 at 13:17 — OMGjava, Apr 03 '12 at 13:17

Avoid printing the last comma

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