Java string split returns empty results

Question

Given input is always going to start with 0 and then follow as: c1 + occurrence where c1 is the character and occurrence is the sequence of the same character repeating. For example aabbaaacccc becomes 0a2b2a3c4, characters will be always lowercase a-z.

Now my issue is given input as: 0x1k1c4t11g3d1m1d1j10f1v1n3e2r3i1e2a1h4a2e1y1z2e1s1a1q1j2r1k2t3h1i1f4j1d2m4p3 However when I use String.split() and iterate through the results I am getting empty strings. I tried using both split("[0-9]") and split("[^a-z]") but result does not change.

The iteration result for my example is:

x
k
c
t

g
d
m
d
j

f
v
n
e
r
i
e
a
h
a
e
y
z
e
s
a
q
j
r
k
t
h
i
f
j
d
m
p

Is this a bug in JDK or is there something wrong with my regex?

When you split on numbers, anytime you have two numbers in a row (like 11), you'll end up seeing an empty string, because there's nothing between those two digits. — FThompson
– FThompson, Commented May 3, 2014 at 19:14

gastisalgado · Accepted Answer · 2014-05-03 20:01:55Z

1

The problem here seems to be that you split by a regex that's is of exactly one number or char, you have an empty string when you get a two digit number for example t11 you get t1 and you loose the final 1, if you want to take the whole number you need to put + after what the regex is looking for, for example in this case you should put. split("[0-9]+") and you would get the whole numbers no matter how many digits you have.

answered May 3, 2014 at 20:01

gastisalgado

261 bronze badge

Sign up to request clarification or add additional context in comments.

Comments

Kostas Kryptos · Accepted Answer · 2014-05-03 19:37:08Z

0

As Vulcan states in his comment, this is caused due to the existence of at least two consecutive numbers which result in empty String. Maybe you would like to remove any numbers from the String first or obviously, remove the empty Strings in your resulted array. for instance:

s = "0x1k1c4t11g3d1m1d1j10f1v1n3e2r3i1e2a1h4a2e1y1z2e1s1a1q1j2r1k2t3h1i1f4j1d2m4p3";    
s = s.replaceAll("\\d","");

answered May 3, 2014 at 19:37

Kostas Kryptos

4,1312 gold badges25 silver badges24 bronze badges

Comments

user3579257 · Accepted Answer · 2014-05-03 20:06:08Z

0

I don't think it is good idea to use String split() in this case. it will be better if you use substring and charAt() in this case, then try to consider a loop that is going to count number of occurrences.

answered May 3, 2014 at 20:06

user3579257

213 bronze badges

Comments

Gras Double · Accepted Answer · 2014-05-03 20:49:13Z

0

You need to split by a zero-length pattern. A lookahead assertion, which is non-capturing, is the way to go:

String str = "0d1j10f1";
str.split("(?=[a-z])");
// result: ["0", "d1", "j10", "f1"]

Also, as pointed out in other answers, keep in mind numbers can be multiple-digit.

edited May 3, 2014 at 20:49

answered May 3, 2014 at 20:40

Gras Double

16.5k9 gold badges61 silver badges56 bronze badges

Collectives™ on Stack Overflow

Java string split returns empty results

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related