java - How can split a string which contains only delimiter?

Question

I am using the following code:

String sample = "::";
String[] splitTime = sample.split(":");
// extra detail omitted
System.out.println("Value 1 :"+splitTime[0]);
System.out.println("Value 2 :"+splitTime[1]);
System.out.println("Value 3 :"+splitTime[2]);

I am getting ArrayIndexOutofBound exception. How does String.split() handle consecutive or trailing / opening delimiters?

See also:

• Doubt in split method
• Java split() method strips empty strings at the end?

Answer 1

Alnitak is correct that trailing empty strings will be discarded by default.

If you want to have trailing empty strings, you should use split(String, int) and pass a negative number as the limit parameter.

The limit parameter controls the number of times the pattern is applied and therefore affects the length of the resulting array. If the limit n is greater than zero then the pattern will be applied at most n - 1 times, the array's length will be no greater than n, and the array's last entry will contain all input beyond the last matched delimiter. If n is non-positive then the pattern will be applied as many times as possible and the array can have any length. 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.

Note that split(aString) is a synonym for split(aString, 0):

This method works as if by invoking the two-argument split method with the given expression and a limit argument of zero. Trailing empty strings are therefore not included in the resulting array.

Also, you should use a loop to get the values from the array; this avoids a possible ArrayIndexOutOfBoundsException.

So your corrected code should be (assuming you want the trailing empty strings):

String sample = "::";
String[] splitTime = sample.split(":", -1);
for (int i = 0; i < splitTime.length; i++) {
    System.out.println("Value " + i + " : "" + splitTime[i] + """);
}

Output:

Value 0 : ""
Value 1 : ""
Value 2 : ""