Stop extra comma and space from being printed out at end of each array

Question

This has been driving me crazy all day. I've been trying to get the arrays to stop printing a comma after the last number that's printed for that array. I just can't seem to get it to work properly. Any help at all would be greatly appreciated.

This is the output of the arrays:

[5, 6, 7, 8, ]

[[2, 4, 6, 8, ] [8, 7, 9, 1, ] [35, 1, 2, ]]

[[12, ] [3, 4, 5, ] [6, ] [7, 8, 9, ]]

The output I want:

[5, 6, 7, 8]

[[2, 4, 6, 8] [8, 7, 9, 1] [3, 5, 1, 2]]

[[1, 2] [3, 4, 5] [6] [7, 8, 9]]

public class ArrayPrinter {

public static void main(String[] args) {
    int[] oneD = {5 ,6 ,7 ,8};
  
    int[][] twoD = {{2, 4, 6, 8}, {8, 7, 9, 1}, {3, 5, 1, 2}}; 
   
    int[][] twoD2 = {{1, 2}, {3, 4, 5}, {6}, {7, 8, 9}};
   
    printArray(oneD);
    printArray(twoD);
    printArray(twoD2);
    
}

public static void printArray(int[] arr) 
{
   int l = arr.length;
    System.out.print("[");
    for (int i = 0; i < l; i++) 
    {
        if (arr [i] == l-1)
            System.out.print(arr[i]);
        
       else
            System.out.print(arr[i] + ", ");
    }
    
    System.out.println("]");
    
}

public static void printArray(int[] [] arr) 
{
    
    int l = arr.length;
    System.out.println("[");
       for (int i=0; i < l; i++) 
        printArray(arr[i]);
    System.out.println("]");
   }
}

You do the same thing whether `arr [i] == l-1` or not; you might want to start there. — Scott Hunter, Nov 27 '16 at 00:22
I'm aware of this, the only problem is if I don't do that, some of the numbers in the array will print as [12, ] instead of [1, 2] — user7214683, Nov 27 '16 at 00:24
When you say "if I don't so that", what are you doing instead? As it is, the `if` is pointltess, because you do exactly the same thing whether the test is true or false. — Scott Hunter, Nov 27 '16 at 00:26
Hmm actually I'll follow your suggestion and update/edit the post as soon as I can. I have a feeling you're right and that the problem with spaces and comma's not printing is related to the way I get the array length. — user7214683, Nov 27 '16 at 00:42
Related http://stackoverflow.com/questions/18279622/print-out-elements-from-an-array-with-a-comma-between-elements-except-the-last-w and http://stackoverflow.com/questions/409784/whats-the-simplest-way-to-print-a-java-array — OneCricketeer, Nov 27 '16 at 01:32
Tried @Scott Hunter's suggestion. Now some of the numbers are printing without a comma or space between them — user7214683, Nov 27 '16 at 02:16

score 0 · Accepted Answer · answered Nov 27 '16 at 02:25

0

If you only want to print a comma after each element that is not the last, you want to check its position, not its value:

if ( i < l-1 )
   System.out.print(arr[i] + ", ");
else
   System.out.print(arr[i]);

answered Nov 27 '16 at 02:25

Scott Hunter

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score 0 · Answer 2 · answered Dec 06 '16 at 16:00

For a solution with no loop or check of indexes, you can use the Arrays.toString method that does exactly what you want for 1D array:

public static void printArray(int[] array) {
    System.out.println(Arrays.toString(array));
}

For 2D arrays then you can use java 8 streams combined with the previous method:

public static void printArray(int[][] array) {
    String arr2d = Arrays.stream(array)             // build a stream of int[]
        .map(x -> Arrays.toString(x))               // format each int[] into a pretty string
        .collect(Collectors.joining("", "[", "]")); // format the 2d array
    System.out.println(arr2d);
}

Stop extra comma and space from being printed out at end of each array

2 Answers2