Mixing
Split regex to extract Strings of contiguous characters
Is there a regex that would work with String.split() to break a String into contiguous characters - ie split where the next character is different to the previous character?
Here's the test case:
String regex = "your answer here";
String parts = "aaabbcddeee".split(regex);
System.out.println(Arrays.toString(parts));
Expected output:
[aaa, bb, c, dd, eee]
Although the test case has letters only as input, this is for clarity only; input characters may be any character.
Please do not provide "work-arounds" involving loops or other techniques.
The question is to find the right regex for the code as shown above - ie only using split() and no other methods calls. It is not a question about finding code that will "do the job".
java regex split
asked Nov 28 '12 at 1:46
Bohemian♦Bohemian
295k64416553
add a comment |
Is there a regex that would work with String.split() to break a String into contiguous characters - ie split where the next character is different to the previous character?
Here's the test case:
String regex = "your answer here";
String parts = "aaabbcddeee".split(regex);
System.out.println(Arrays.toString(parts));
Expected output:
[aaa, bb, c, dd, eee]
Although the test case has letters only as input, this is for clarity only; input characters may be any character.
Please do not provide "work-arounds" involving loops or other techniques.
The question is to find the right regex for the code as shown above - ie only using split() and no other methods calls. It is not a question about finding code that will "do the job".
java regex split
asked Nov 28 '12 at 1:46
Bohemian♦Bohemian
295k64416553
add a comment |
Is there a regex that would work with String.split() to break a String into contiguous characters - ie split where the next character is different to the previous character?
Here's the test case:
String regex = "your answer here";
String parts = "aaabbcddeee".split(regex);
System.out.println(Arrays.toString(parts));
Expected output:
[aaa, bb, c, dd, eee]
Although the test case has letters only as input, this is for clarity only; input characters may be any character.
Please do not provide "work-arounds" involving loops or other techniques.
The question is to find the right regex for the code as shown above - ie only using split() and no other methods calls. It is not a question about finding code that will "do the job".
java regex split
asked Nov 28 '12 at 1:46
Bohemian♦Bohemian
295k64416553
Is there a regex that would work with String.split() to break a String into contiguous characters - ie split where the next character is different to the previous character?
Here's the test case:
String regex = "your answer here";
String parts = "aaabbcddeee".split(regex);
System.out.println(Arrays.toString(parts));
Expected output:
[aaa, bb, c, dd, eee]
Although the test case has letters only as input, this is for clarity only; input characters may be any character.
Please do not provide "work-arounds" involving loops or other techniques.
The question is to find the right regex for the code as shown above - ie only using split() and no other methods calls. It is not a question about finding code that will "do the job".
java regex split
java regex split
asked Nov 28 '12 at 1:46
Bohemian♦Bohemian
295k64416553
asked Nov 28 '12 at 1:46
Bohemian♦Bohemian
295k64416553
edited Nov 28 '12 at 2:05
Bohemian
asked Nov 28 '12 at 1:46
Bohemian♦Bohemian
295k64416553
asked Nov 28 '12 at 1:46
Bohemian♦Bohemian
295k64416553
asked Nov 28 '12 at 1:46
Bohemian♦Bohemian
295k64416553
295k64416553
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
It is totally possible to write the regex for splitting in one step:
"(?<=(.))(?!\1)"
Since you want to split between every group of same characters, we just need to look for the boundary between 2 groups. I achieve this by using a positive look-behind just to grab the previous character, and use a negative look-ahead and back-reference to check that the next character is not the same character.
As you can see, the regex is zero-width (only 2 look around assertions). No character is consumed by the regex.
answered Nov 28 '12 at 2:17
nhahtdhnhahtdh
47.6k1291130
2
+1 Success.
– nickb
Nov 28 '12 at 2:18
1
+1 Nice one, I'll make a note of this for the future.
– arshajii
Nov 28 '12 at 2:20
Ooh, nice! :) +1 more
– Amadan
Nov 28 '12 at 2:28
+1 Good job. Not being sour grapes, but I tried that except I coded the look ahead as(?!=\1)thinking!=like the java boolean comparison. Doh!
– Bohemian♦
Nov 28 '12 at 7:42
in.netcharacter within the group i.e(.)is also included in the result..i wonder why it's not the case withjava
– Anirudha
Nov 28 '12 at 8:17
|
show 1 more comment
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1 Answer
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active
oldest
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
It is totally possible to write the regex for splitting in one step:
"(?<=(.))(?!\1)"
Since you want to split between every group of same characters, we just need to look for the boundary between 2 groups. I achieve this by using a positive look-behind just to grab the previous character, and use a negative look-ahead and back-reference to check that the next character is not the same character.
As you can see, the regex is zero-width (only 2 look around assertions). No character is consumed by the regex.
answered Nov 28 '12 at 2:17
nhahtdhnhahtdh
47.6k1291130
2
+1 Success.
– nickb
Nov 28 '12 at 2:18
1
+1 Nice one, I'll make a note of this for the future.
– arshajii
Nov 28 '12 at 2:20
Ooh, nice! :) +1 more
– Amadan
Nov 28 '12 at 2:28
+1 Good job. Not being sour grapes, but I tried that except I coded the look ahead as(?!=\1)thinking!=like the java boolean comparison. Doh!
– Bohemian♦
Nov 28 '12 at 7:42
in.netcharacter within the group i.e(.)is also included in the result..i wonder why it's not the case withjava
– Anirudha
Nov 28 '12 at 8:17
|
show 1 more comment
It is totally possible to write the regex for splitting in one step:
"(?<=(.))(?!\1)"
Since you want to split between every group of same characters, we just need to look for the boundary between 2 groups. I achieve this by using a positive look-behind just to grab the previous character, and use a negative look-ahead and back-reference to check that the next character is not the same character.
As you can see, the regex is zero-width (only 2 look around assertions). No character is consumed by the regex.
answered Nov 28 '12 at 2:17
nhahtdhnhahtdh
47.6k1291130
2
+1 Success.
– nickb
Nov 28 '12 at 2:18
1
+1 Nice one, I'll make a note of this for the future.
– arshajii
Nov 28 '12 at 2:20
Ooh, nice! :) +1 more
– Amadan
Nov 28 '12 at 2:28
+1 Good job. Not being sour grapes, but I tried that except I coded the look ahead as(?!=\1)thinking!=like the java boolean comparison. Doh!
– Bohemian♦
Nov 28 '12 at 7:42
in.netcharacter within the group i.e(.)is also included in the result..i wonder why it's not the case withjava
– Anirudha
Nov 28 '12 at 8:17
|
show 1 more comment
It is totally possible to write the regex for splitting in one step:
"(?<=(.))(?!\1)"
Since you want to split between every group of same characters, we just need to look for the boundary between 2 groups. I achieve this by using a positive look-behind just to grab the previous character, and use a negative look-ahead and back-reference to check that the next character is not the same character.
As you can see, the regex is zero-width (only 2 look around assertions). No character is consumed by the regex.
answered Nov 28 '12 at 2:17
nhahtdhnhahtdh
47.6k1291130
It is totally possible to write the regex for splitting in one step:
"(?<=(.))(?!\1)"
Since you want to split between every group of same characters, we just need to look for the boundary between 2 groups. I achieve this by using a positive look-behind just to grab the previous character, and use a negative look-ahead and back-reference to check that the next character is not the same character.
As you can see, the regex is zero-width (only 2 look around assertions). No character is consumed by the regex.
answered Nov 28 '12 at 2:17
nhahtdhnhahtdh
47.6k1291130
answered Nov 28 '12 at 2:17
nhahtdhnhahtdh
47.6k1291130
answered Nov 28 '12 at 2:17
nhahtdhnhahtdh
47.6k1291130
answered Nov 28 '12 at 2:17
nhahtdhnhahtdh
47.6k1291130
47.6k1291130
2
+1 Success.
– nickb
Nov 28 '12 at 2:18
1
+1 Nice one, I'll make a note of this for the future.
– arshajii
Nov 28 '12 at 2:20
Ooh, nice! :) +1 more
– Amadan
Nov 28 '12 at 2:28
+1 Good job. Not being sour grapes, but I tried that except I coded the look ahead as(?!=\1)thinking!=like the java boolean comparison. Doh!
– Bohemian♦
Nov 28 '12 at 7:42
in.netcharacter within the group i.e(.)is also included in the result..i wonder why it's not the case withjava
– Anirudha
Nov 28 '12 at 8:17
|
show 1 more comment
2
+1 Success.
– nickb
Nov 28 '12 at 2:18
1
+1 Nice one, I'll make a note of this for the future.
– arshajii
Nov 28 '12 at 2:20
Ooh, nice! :) +1 more
– Amadan
Nov 28 '12 at 2:28
+1 Good job. Not being sour grapes, but I tried that except I coded the look ahead as(?!=\1)thinking!=like the java boolean comparison. Doh!
– Bohemian♦
Nov 28 '12 at 7:42
in.netcharacter within the group i.e(.)is also included in the result..i wonder why it's not the case withjava
– Anirudha
Nov 28 '12 at 8:17
2
2
+1 Success.
– nickb
Nov 28 '12 at 2:18
+1 Success.
– nickb
Nov 28 '12 at 2:18
1
1
+1 Nice one, I'll make a note of this for the future.
– arshajii
Nov 28 '12 at 2:20
+1 Nice one, I'll make a note of this for the future.
– arshajii
Nov 28 '12 at 2:20
Ooh, nice! :) +1 more
– Amadan
Nov 28 '12 at 2:28
Ooh, nice! :) +1 more
– Amadan
Nov 28 '12 at 2:28
+1 Good job. Not being sour grapes, but I tried that except I coded the look ahead as
(?!=\1) thinking != like the java boolean comparison. Doh!– Bohemian♦
Nov 28 '12 at 7:42
+1 Good job. Not being sour grapes, but I tried that except I coded the look ahead as
(?!=\1) thinking != like the java boolean comparison. Doh!– Bohemian♦
Nov 28 '12 at 7:42
in
.net character within the group i.e (.) is also included in the result..i wonder why it's not the case with java– Anirudha
Nov 28 '12 at 8:17
in
.net character within the group i.e (.) is also included in the result..i wonder why it's not the case with java– Anirudha
Nov 28 '12 at 8:17
|
show 1 more comment
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