How to read only first expression of my file and move to another line

Question

I have a file that looks like follows:

What I need is to read only names (first column) and output it.

  while (sc.hasNext()) 
     System.out.println(sc.next());

Another solution I tried is:

  while (sc.hasNextLine()) 
     System.out.println(sc.nextLine());

The ones that are above obviously don't work. I am stuck and don't know what to do. I was trying to google my problem but couldn't find the answer.

Read the line into a variable then split on space `str.split("\\s+")` and print the column you're interested in: https://repl.it/repls/TestySeashellFibonacci — Nir Alfasi, Aug 14 '19 at 23:16

score 1 · Accepted Answer · answered Aug 14 '19 at 23:31

1

while(sc.hasNextLine()) {
    StringBuilder toPrint = new StringBuilder();
    String line = sc.nextLine();

    for(int i = 0; i < line.length() && line.charAt(i) != ' '; i ++) {
        toPrint.append(line.charAt(i));
    }

    System.out.println(toPrint.toString());
}

The reason I don't use String.split() is because that does lot's of unnecessary work, as it splits the entire string, and you only want the first word.

answered Aug 14 '19 at 23:31

nishantc1527

376
1
12

You can use `substring` and avoid the loop? – Subir Kumar Sao Aug 15 '19 at 00:39
However you don't know how big the word is. – nishantc1527 Aug 15 '19 at 00:40
`indexOf` to get the first space. – Subir Kumar Sao Aug 15 '19 at 00:41
That will work, but I think it will be to slow because it searches the array for a space, then `subString()` itself is slow because it works by concatenating, which is a slow process. – nishantc1527 Aug 15 '19 at 00:43

How to read only first expression of my file and move to another line

1 Answers1