Using Pattern and Matcher to search for special characters (Example: $)
Apologies if this has already been answered.
I am using the following code to search for a substring:
String subject = "ABC"
String subString = "AB"
Pattern pattern = Pattern.compile(subString, Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(subject);
while (matcher.find()){
//Matched
}
But when my subject string contains a $ in the beginning, it does not work since it is a special character.
String subject = "$ABC"
String subString = "$"
How does one handle that?
java regex pattern-matching
asked Nov 20 '18 at 1:34
SunnySunny
2,700144578
add a comment |
Apologies if this has already been answered.
I am using the following code to search for a substring:
String subject = "ABC"
String subString = "AB"
Pattern pattern = Pattern.compile(subString, Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(subject);
while (matcher.find()){
//Matched
}
But when my subject string contains a $ in the beginning, it does not work since it is a special character.
String subject = "$ABC"
String subString = "$"
How does one handle that?
java regex pattern-matching
asked Nov 20 '18 at 1:34
SunnySunny
2,700144578
add a comment |
Apologies if this has already been answered.
I am using the following code to search for a substring:
String subject = "ABC"
String subString = "AB"
Pattern pattern = Pattern.compile(subString, Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(subject);
while (matcher.find()){
//Matched
}
But when my subject string contains a $ in the beginning, it does not work since it is a special character.
String subject = "$ABC"
String subString = "$"
How does one handle that?
java regex pattern-matching
asked Nov 20 '18 at 1:34
SunnySunny
2,700144578
Apologies if this has already been answered.
I am using the following code to search for a substring:
String subject = "ABC"
String subString = "AB"
Pattern pattern = Pattern.compile(subString, Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(subject);
while (matcher.find()){
//Matched
}
But when my subject string contains a $ in the beginning, it does not work since it is a special character.
String subject = "$ABC"
String subString = "$"
How does one handle that?
java regex pattern-matching
java regex pattern-matching
asked Nov 20 '18 at 1:34
SunnySunny
2,700144578
asked Nov 20 '18 at 1:34
SunnySunny
2,700144578
asked Nov 20 '18 at 1:34
SunnySunny
2,700144578
asked Nov 20 '18 at 1:34
SunnySunny
2,700144578
asked Nov 20 '18 at 1:34
SunnySunny
2,700144578
2,700144578
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
By escaping the special character in the subString. Like,
String subString = "\$";
or telling the Pattern to match literals. Like,
Pattern pattern = Pattern.compile(subString, Pattern.LITERAL | Pattern.CASE_INSENSITIVE);
answered Nov 20 '18 at 1:37
Elliott FrischElliott Frisch
154k1393182
1
If you don't know in advance what you're searching for,Pattern.quoteis your friend.
– Amadan
Nov 20 '18 at 1:43
add a comment |
There are few meta characters in regex. And some of them which are supported by regex in java are
( ) [ ] { { ^ $ | ? * + . < > - = !
So $ is a indeed meta character here. The meta character conveys special meaning to the regex engine and hence can't be use literally. So in order to use them you have to combine them with escape character which is backslash
So String subject = "\$ABC"
String subString = "\$"
would do. Java uses double backslash instead of single for escape character unlike the other regex engine.
answered Nov 20 '18 at 1:45
Brij Raj KishoreBrij Raj Kishore
1,0201418
2
"Java uses double backslash instead of single" is incorrect; Java uses single backslash just like other regexes. For example, if you look at your "subject" or "substring" variables in the debugger as the program is running, you would find the string value contains a single backslash. The need for the double-backslash is purely to escape the backslash for a String value (similar to "n", etc), not for the Regex.
– racraman
Nov 20 '18 at 1:54
yes. My bad I just forget it is the case of escape character
– Brij Raj Kishore
Nov 20 '18 at 1:57
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
By escaping the special character in the subString. Like,
String subString = "\$";
or telling the Pattern to match literals. Like,
Pattern pattern = Pattern.compile(subString, Pattern.LITERAL | Pattern.CASE_INSENSITIVE);
answered Nov 20 '18 at 1:37
Elliott FrischElliott Frisch
154k1393182
1
If you don't know in advance what you're searching for,Pattern.quoteis your friend.
– Amadan
Nov 20 '18 at 1:43
add a comment |
By escaping the special character in the subString. Like,
String subString = "\$";
or telling the Pattern to match literals. Like,
Pattern pattern = Pattern.compile(subString, Pattern.LITERAL | Pattern.CASE_INSENSITIVE);
answered Nov 20 '18 at 1:37
Elliott FrischElliott Frisch
154k1393182
1
If you don't know in advance what you're searching for,Pattern.quoteis your friend.
– Amadan
Nov 20 '18 at 1:43
add a comment |
By escaping the special character in the subString. Like,
String subString = "\$";
or telling the Pattern to match literals. Like,
Pattern pattern = Pattern.compile(subString, Pattern.LITERAL | Pattern.CASE_INSENSITIVE);
answered Nov 20 '18 at 1:37
Elliott FrischElliott Frisch
154k1393182
By escaping the special character in the subString. Like,
String subString = "\$";
or telling the Pattern to match literals. Like,
Pattern pattern = Pattern.compile(subString, Pattern.LITERAL | Pattern.CASE_INSENSITIVE);
answered Nov 20 '18 at 1:37
Elliott FrischElliott Frisch
154k1393182
answered Nov 20 '18 at 1:37
Elliott FrischElliott Frisch
154k1393182
answered Nov 20 '18 at 1:37
Elliott FrischElliott Frisch
154k1393182
answered Nov 20 '18 at 1:37
Elliott FrischElliott Frisch
154k1393182
154k1393182
1
If you don't know in advance what you're searching for,Pattern.quoteis your friend.
– Amadan
Nov 20 '18 at 1:43
add a comment |
1
If you don't know in advance what you're searching for,Pattern.quoteis your friend.
– Amadan
Nov 20 '18 at 1:43
1
1
If you don't know in advance what you're searching for,
Pattern.quote is your friend.– Amadan
Nov 20 '18 at 1:43
If you don't know in advance what you're searching for,
Pattern.quote is your friend.– Amadan
Nov 20 '18 at 1:43
add a comment |
There are few meta characters in regex. And some of them which are supported by regex in java are
( ) [ ] { { ^ $ | ? * + . < > - = !
So $ is a indeed meta character here. The meta character conveys special meaning to the regex engine and hence can't be use literally. So in order to use them you have to combine them with escape character which is backslash
So String subject = "\$ABC"
String subString = "\$"
would do. Java uses double backslash instead of single for escape character unlike the other regex engine.
answered Nov 20 '18 at 1:45
Brij Raj KishoreBrij Raj Kishore
1,0201418
2
"Java uses double backslash instead of single" is incorrect; Java uses single backslash just like other regexes. For example, if you look at your "subject" or "substring" variables in the debugger as the program is running, you would find the string value contains a single backslash. The need for the double-backslash is purely to escape the backslash for a String value (similar to "n", etc), not for the Regex.
– racraman
Nov 20 '18 at 1:54
yes. My bad I just forget it is the case of escape character
– Brij Raj Kishore
Nov 20 '18 at 1:57
add a comment |
There are few meta characters in regex. And some of them which are supported by regex in java are
( ) [ ] { { ^ $ | ? * + . < > - = !
So $ is a indeed meta character here. The meta character conveys special meaning to the regex engine and hence can't be use literally. So in order to use them you have to combine them with escape character which is backslash
So String subject = "\$ABC"
String subString = "\$"
would do. Java uses double backslash instead of single for escape character unlike the other regex engine.
answered Nov 20 '18 at 1:45
Brij Raj KishoreBrij Raj Kishore
1,0201418
2
"Java uses double backslash instead of single" is incorrect; Java uses single backslash just like other regexes. For example, if you look at your "subject" or "substring" variables in the debugger as the program is running, you would find the string value contains a single backslash. The need for the double-backslash is purely to escape the backslash for a String value (similar to "n", etc), not for the Regex.
– racraman
Nov 20 '18 at 1:54
yes. My bad I just forget it is the case of escape character
– Brij Raj Kishore
Nov 20 '18 at 1:57
add a comment |
There are few meta characters in regex. And some of them which are supported by regex in java are
( ) [ ] { { ^ $ | ? * + . < > - = !
So $ is a indeed meta character here. The meta character conveys special meaning to the regex engine and hence can't be use literally. So in order to use them you have to combine them with escape character which is backslash
So String subject = "\$ABC"
String subString = "\$"
would do. Java uses double backslash instead of single for escape character unlike the other regex engine.
answered Nov 20 '18 at 1:45
Brij Raj KishoreBrij Raj Kishore
1,0201418
There are few meta characters in regex. And some of them which are supported by regex in java are
( ) [ ] { { ^ $ | ? * + . < > - = !
So $ is a indeed meta character here. The meta character conveys special meaning to the regex engine and hence can't be use literally. So in order to use them you have to combine them with escape character which is backslash
So String subject = "\$ABC"
String subString = "\$"
would do. Java uses double backslash instead of single for escape character unlike the other regex engine.
answered Nov 20 '18 at 1:45
Brij Raj KishoreBrij Raj Kishore
1,0201418
edited Nov 20 '18 at 1:57
answered Nov 20 '18 at 1:45
Brij Raj KishoreBrij Raj Kishore
1,0201418
answered Nov 20 '18 at 1:45
Brij Raj KishoreBrij Raj Kishore
1,0201418
answered Nov 20 '18 at 1:45
Brij Raj KishoreBrij Raj Kishore
1,0201418
1,0201418
2
"Java uses double backslash instead of single" is incorrect; Java uses single backslash just like other regexes. For example, if you look at your "subject" or "substring" variables in the debugger as the program is running, you would find the string value contains a single backslash. The need for the double-backslash is purely to escape the backslash for a String value (similar to "n", etc), not for the Regex.
– racraman
Nov 20 '18 at 1:54
yes. My bad I just forget it is the case of escape character
– Brij Raj Kishore
Nov 20 '18 at 1:57
add a comment |
2
"Java uses double backslash instead of single" is incorrect; Java uses single backslash just like other regexes. For example, if you look at your "subject" or "substring" variables in the debugger as the program is running, you would find the string value contains a single backslash. The need for the double-backslash is purely to escape the backslash for a String value (similar to "n", etc), not for the Regex.
– racraman
Nov 20 '18 at 1:54
yes. My bad I just forget it is the case of escape character
– Brij Raj Kishore
Nov 20 '18 at 1:57
2
2
"Java uses double backslash instead of single" is incorrect; Java uses single backslash just like other regexes. For example, if you look at your "subject" or "substring" variables in the debugger as the program is running, you would find the string value contains a single backslash. The need for the double-backslash is purely to escape the backslash for a String value (similar to "n", etc), not for the Regex.
– racraman
Nov 20 '18 at 1:54
"Java uses double backslash instead of single" is incorrect; Java uses single backslash just like other regexes. For example, if you look at your "subject" or "substring" variables in the debugger as the program is running, you would find the string value contains a single backslash. The need for the double-backslash is purely to escape the backslash for a String value (similar to "n", etc), not for the Regex.
– racraman
Nov 20 '18 at 1:54
yes. My bad I just forget it is the case of escape character
– Brij Raj Kishore
Nov 20 '18 at 1:57
yes. My bad I just forget it is the case of escape character
– Brij Raj Kishore
Nov 20 '18 at 1:57
add a comment |
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