Adding commas to output

Question

This is what it does:

2,
4,
6,
8,
10

I would like for it to be horizontal: 2, 4, 6, 8, 10

        try    { 
            PrintWriter fout = new PrintWriter(new BufferedWriter(new FileWriter("numbers.dat"))); 
            for(int i = start; i <= 100; i = i + 2)    { 
                fout.println(i+","); 
            }

possible duplicate of [Clearest way to comma-delimit a list (Java)?](http://stackoverflow.com/questions/668952/clearest-way-to-comma-delimit-a-list-java) — wkl, Mar 28 '11 at 16:31
println prints the string passed to it and then a newline character. So if you want to print all the data on the dame line, then use print rather than println which is same as println, but doesn't insert a newline character after the message. — Logan, Mar 28 '11 at 17:47
@Logan: That worked, is there a way to remove the last comma. It ends like this: 100, — Mike, Mar 28 '11 at 17:50

score 2 · Answer 1 · answered Mar 28 '11 at 16:39

2

Another attempt

for(int i = start; i <= 100; i += 2) 
    System.out.print(i + (i > 98 ? "\n" : ", "));

answered Mar 28 '11 at 16:39

Peter Lawrey

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Jeremy · Answer 2 · 2011-03-28T16:46:56.030

1

Here is a very basic example of what you could do:

int max=11;
for(int i = 0; i < max; i += 2){
    System.out.print(i);
    if(i < max-2){
        System.out.print(", ");
    }
}

edited Mar 28 '11 at 16:46

answered Mar 28 '11 at 16:31

Jeremy

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I think you meant `i = start` and if `(i < max-2)` – MByD Mar 28 '11 at 16:35
@MByD: For the purpose of my example `i` starts at `0`. And, since we are incrementing by `2`, I agree with your second amendment. – Jeremy Mar 28 '11 at 16:49

Buhake Sindi · Accepted Answer · 2011-03-28T16:49:56.227

1

In the write() method:

 for(int i = start; i <= 100; i = i + 2)    { 
    if (i > start) {
        fout.print(",");
    }

    fout.println(i); 
}

Then when you call output(), it will display as comma separated list. And for screen display

while((outputline = fin.readLine()) != null) { 
    System.out.print(outputline + " "); 
}
System.out.println();

Alternatively, skip saving the comma in the file and displaying will be as follows

int count = 0;
while((outputline = fin.readLine()) != null) { 
    if (count > 0)
        System.out.print(", ");

    System.out.print(outputline); 
    count++;
}
System.out.println();

edited Mar 28 '11 at 16:49

answered Mar 28 '11 at 16:32

Buhake Sindi

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@The Elite Gentleman: That added the comma, but it still is in column format and not row. Also there isn't a comma between 2 & 4. It goes 2 4, 6, 8, 10. – Mike Mar 28 '11 at 16:37
@The Gentlemen - he'll get 2 4, 6, 8, ... 100, – MByD Mar 28 '11 at 16:38
@Mike, I did the change, but I don't understand how you file format structure must be like. – Buhake Sindi Mar 28 '11 at 16:40
@ The Elite Gentleman: I looked over your code, but am not sure where to input it. I've tried several ways, but get errors. – Mike Mar 28 '11 at 17:11
@Mike, just substitute your loops with mine. – Buhake Sindi Mar 28 '11 at 17:59

justkt · Answer 4 · 2011-03-28T16:38:55.150

If you mean to do it on printing to your .dat file:

 for(int i = start; i <= 100; i = i + 2) { 
     fout.print(i);
     if(i < 100) {
         fout.print(", ");
     } else {
         fout.println();
     }
  }

If it is when printing to the system output after reading your file, try this:

      try    { 
        BufferedReader fin = new BufferedReader(new FileReader("numbers.dat")); 

            String outputline = ""; 
            StringBuilder result = new StringBuilder();
            while((outputline = fin.readLine()) != null)    { 
            result.append(outputline).append(", "); 
            } 
            int length = result.length();
            result.delete(length - 2, length);
            System.out.println(result);
            fin.close(); 
        }

This uses a StringBuilder to build up your result and then removes the last , when it is done.

I meant it appears the OP wants the output all on the same line, as it is in the example. ;) — Peter Lawrey, Mar 28 '11 at 16:41

score 0 · Answer 5 · answered Mar 28 '11 at 16:32

0

fout.println(i + ", ");  

System.out.println(outputline + ", ");

This will give you commas after all the numbers but it looks like you don't need one after the final number.

You will have to remove the last comma either by using indexOf or checking for the last iteration of your loop.

answered Mar 28 '11 at 16:32

blong824

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You don't have a clue on the file format of `numbers.dat`, what makes you sure that your code for file reading & displaying will work? – Buhake Sindi Mar 28 '11 at 16:35

Adding commas to output

5 Answers5