How to use split function when input is new line?

Short answer: To get the tokens in str (determined by whitespace separators), you can do the following:

String str = ... //some string str = str.trim() + " "; //modify the string for the reasons described below String[] tokens = str.split("\\s+"); 

Longer answer:

First of all, the argument to split() is the delimiter - in this case one or more whitespace characters, which is "\\s+".

If you look carefully at the Javadoc of String#split(String, int) (which is what String#split(String) calls), you will see why it behaves like this.

If the expression does not match any part of the input then the resulting array has just one element, namely this string.

This is why "".split("\\s+") would return an array with one empty string [""], so you need to append the space to avoid this. " ".split("\\s+") returns an empty array with 0 elements, as you want.

When there is a positive-width match at the beginning of this string then an empty leading substring is included at the beginning of the resulting array.

This is why " a".split("\\s+") would return ["", "a"], so you need to trim() the string first to remove whitespace from the beginning.

If n is zero then the pattern will be applied as many times as possible, the array can have any length, and trailing empty strings will be discarded.

Since String#split(String) calls String#split(String, int) with the limit argument of zero, you can add whitespace to the end of the string without changing the number of words (because trailing empty strings will be discarded).

UPDATE:

If the delimiter is "\\W+", it's slightly different because you can't use trim() for that:

String str = ... str = str.replaceAll("^\\W+", "") + " "; String[] tokens = str.split("\\W+"); 

public static void main(String[] args) { Scanner in = new Scanner(System.in); String line = null; while (!(line = in.nextLine()).isEmpty()) { //logic } System.out.print("Empty Line"); } 

output

Empty Line