以8行打印一个列表（java）

Question

I need to print a list in lines of 8. Say if the list was integers long it would print 8 on the first row and 2 on the next. Here is my code:

for(int i = 0; i < size; i++){
    System.out.println(list[i] + " ");
}

How could I print it in lines of 8 instead of printing one per line?

Answer 1

Use StringBuilder :

 StringBuilder sb = new StringBuilder();
 sb.append(list[0]).append(" ");
 for (int i = 1 ; i < size; i++) {
      sb.append(list[i]).append(" ");
      if ( (i + 1) % 8 == 0 ) { sb.append("\n"); }
 }
 System.out.print(sb.toString());

Answer 2

Every answer I've seen until now has a bug in where it breaks. Use the following:

int[] list = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18};

int br = 8;
for (int i = 0; i < list.length; i++) {
    System.out.print(list[i] + " ");
    if (i % br == (br - 1))
        System.out.println();
}

Or:

int br = 8;
for (int i = 0; i < list.length; i++) {
    if (i > 0 && i % br == 0)
        System.out.println();
    System.out.print(list[i] + " ");
}

Output:

1 2 3 4 5 6 7 8 
9 10 11 12 13 14 15 16 
17 18 

Here are some ways (taken from other answers to this question) that this cannot be done.

• Break when i % 8 == 0 . This doesn't work because 0 % 8 == 0 is true, which means this will cause a break after the first element.
• Print the item first and then break when i > 0 && (i % 8 == 0) . This does not work because arrays are zero-indexed (eg i does not equal 8 until the 9th element. In other words, you'll have 9 items on the first line. However, this works if you check for the break before printing the element.
• Print out the first item and then start the loop index at 1 . This suffers from the same problem as the previous answer; you'll still always be one index behind.

You can use a StringBuilder to make this marginally faster, but it's more important to get a correct answer than a fast one.

Answer 3

for (int i = 0; i < size; i++) {
  System.out.print(list[i]);
  if (i % 8 == 7) {
    System.out.println();
  } else {
    System.out.print(" ");
  }
}
if (size % 8 != 0) {
  System.out.println();
}

Technically, print("\\n") and println() do not necessarily have the same effect, which is why the above doesn't just do System.out.print((i % 8 ==7) ? "\\n" : " ") .

The extra if is to ensure that the last line is terminated even if it has fewer than 8 elements.

Answer 4

To use Guava... Lists.partition breaks a list into a list of lists with a max length.

List<String> myList;
for (List<String> subs : Lists.partition(myList, 8)){
   System.out.println(Joiner.on(" ").join(subs));
}

Lists.partition

Answer 5

for (int i = 0; i < size; i++)
{
    if ((i % 8 == 0) && (i > 0))
    {
        System.out.println();
    }
    System.out.print(list[i] + " ");
}

Answer 6

for(int i = 0; i < size; i++){
    System.out.println(list[i] + "\n");
}

\\n is for new line.

Answer 7

for (int nI = 0; nI < list.size(); nI++)
{
  System.out.print(list[nI] + " ");

  // new line if you hit 8th, 16th, etc. item in the list
  if (nI > 1 && ((nI+1) % 8 == 0))
    System.out.print("\n");
}