Java Split() Method Strips Empty Strings at the End

Java String split removed empty values

split(delimiter) by default removes trailing empty strings from result array. To turn this mechanism off we need to use overloaded version of split(delimiter, limit) with limit set to negative value like

String[] split = data.split("\\|", -1);

Little more details:

split(regex) internally returns result of split(regex, 0) and in documentation of this method you can find (emphasis mine)

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.

Exception:

It is worth mentioning that removing trailing empty string makes sense only if such empty strings were created by the split mechanism. So for "".split(anything) since we can't split "" farther we will get as result [""] array.

It happens because split didn't happen here, so "" despite being empty and trailing represents original string, not empty string which was created by splitting process.

How to prevent java.lang.String.split() from creating a leading empty string?

Your best bet is probably just to strip out any leading delimiter:

String input = "/Test/Stuff";
String[] test = input.replaceFirst("^/", "").split("/");

You can make it more generic by putting it in a method:

public String[] mySplit(final String input, final String delim)
{
    return input.replaceFirst("^" + delim, "").split(delim);
}

String[] test = mySplit("/Test/Stuff", "/");

String#split. Side effect of limit parameter

Citing Johannes Weiß:

"When calling String.split(String), it calls String.split(String, 0) and that discards trailing empty strings (as the docs say it), when calling String.split(String, n) with n < 0 it won't discard anything."

String split method returning first element as empty using regex

You should use matching. Change your expression to:

`^\[(.*?)\.\.(.*)\]$`

And get your results from the two captured groups.

As for why split acts this way, it's simple: you asked it to split on the [ character, but there's still an "empty string" between the start of the string and the first [ character.

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