Programming Forums > Application Development > Java

larry · Jun 6th, 2006, 9:20 PM

Hi! I am new to pattern matching and need some quick help. I want user to be able to enter in a string and have it match against another string.

if they enter "jo.n sm.th" I need it to match to "john smith"

I'm still learning the matching rules and am hoping you can help me with the above example so I can learn a little faster. Thank you. I appreciate your help.

Booooze · Jun 6th, 2006, 9:30 PM

What you need is a 'wildcard'. In case you haven't heard of them, they do basicly exactly what you want. In your case it would take the '.' and match the rest of the letters, allowing the place where the period is too be any letter. Java has support for this by the looks of it. Try Google. I can't give ya much else on this, but you also might want to consider looking into Regular expressions.

larry · Jun 6th, 2006, 9:34 PM

yeah I know it has a Pattern and Matcher class.

Pattern pat = Pattern.compile(find); //need to put pattern here
Matcher m = pat.matcher(tarray[2]);
if(m.find())

I'm trying to let the user enter in a name and have it match against tarray[2]. I'd prefer if the user could enter jo.n smi.h and have the matcher find it.

I'm hoping someone that knows regular expressions can help me out.

titaniumdecoy · Jun 6th, 2006, 11:04 PM

Assuming you want a period in the input string to match any character in the string you are matching it against, the following code will suffice:

(Toggle Plain Text)

String input = "jo.n sm.th";
String match = "john smith";
boolean matches = match.matches(input);
System.out.println(matches);

Since a period (.) represents any single character in a regular expression, we can simply feed the input string into the String.matches(String regex) method and determine whether the result is true or false.

However, this method has obvious drawbacks; for example, the input string ".*" will match anything. I would suggest finding a way to escape any characters that could be used in regular expressions (except for periods) by prefixing them with a backslash, or if that's too complicated, simply stripping them out.

You can also use the Pattern/Matcher classes (in java.util.regex) if you prefer:

(Toggle Plain Text)

String input = "jo.n sm.th";
String match = "john smith";
Pattern compiledRegex = Pattern.compile(input);
Matcher regexMatcher = compiledRegex.matcher(match);
System.out.println(regexMatcher.matches());

I'm not an expert at using regular expressions, so there may be a better way to go about this.

larry · Jun 6th, 2006, 11:42 PM

I really appreciate your help. The code examples are helping me. Your example is very close and I think I am getting somewhere with it. Thank you.

I have a String named find that contains a name passed from the user. I need to compare it to a name in a file, which is tarray[2]. I am trying to find a way so the user can enter in let's say jo.n smi.h and it compares it to tarray[2]. If it doesn't match it goes to the next record. Maybe even john sm*.

My initial code just compared two strings, but that wasn't good enough because they had to match exactly.

I appreciate evreyone's help. Thank you.

titaniumdecoy · Jun 7th, 2006, 12:11 AM

I would recommend first removing all non-alphanumeric characters (excepting "."), then replacing any occurences of "." with "*". That way any occurences of "." in the input text will match anything, so "jo.n sm.th" will match "john smith", "jonathan epsilon smoog tooth", etc. If that's not what you're looking for, you'll have to be more specific about exactly what you want to match.

titaniumdecoy · Jun 7th, 2006, 12:23 PM

Small correction to my last post: "." should become ".*", not "*".

Jun 6th, 2006, 9:20 PM	#1
larry Newbie Join Date: Jun 2006 Posts: 3 Rep Power: 0	need pattern matching help Hi! I am new to pattern matching and need some quick help. I want user to be able to enter in a string and have it match against another string. if they enter "jo.n sm.th" I need it to match to "john smith" I'm still learning the matching rules and am hoping you can help me with the above example so I can learn a little faster. Thank you. I appreciate your help. Last edited by larry; Jun 6th, 2006 at 9:41 PM.

Jun 6th, 2006, 11:04 PM	#4
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 908 Rep Power: 3	Assuming you want a period in the input string to match any character in the string you are matching it against, the following code will suffice: (Toggle Plain Text) String input = "jo.n sm.th"; String match = "john smith"; boolean matches = match.matches(input); System.out.println(matches); String input = "jo.n sm.th"; String match = "john smith"; boolean matches = match.matches(input); System.out.println(matches); Since a period (.) represents any single character in a regular expression, we can simply feed the input string into the String.matches(String regex) method and determine whether the result is true or false. However, this method has obvious drawbacks; for example, the input string "." will match anything. I would suggest finding a way to escape any characters that could be used in regular expressions (except for periods) by prefixing them with a backslash, or if that's too complicated, simply stripping them out. You can also use the Pattern/Matcher classes (in java.util.regex) if you prefer: (Toggle Plain Text) String input = "jo.n sm.th"; String match = "john smith"; Pattern compiledRegex = Pattern.compile(input); Matcher regexMatcher = compiledRegex.matcher(match); System.out.println(regexMatcher.matches()); String input = "jo.n sm.th"; String match = "john smith"; Pattern compiledRegex = Pattern.compile(input); Matcher regexMatcher = compiledRegex.matcher(match); System.out.println(regexMatcher.matches()); I'm not an expert at using regular expressions, so there may be a better way to go about this. Last edited by titaniumdecoy; Jun 6th, 2006 at 11:22 PM.*

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Jun 6th, 2006, 9:30 PM	#2
Booooze Expert Programmer Join Date: Mar 2006 Location: Igloo Posts: 710 Rep Power: 3	What you need is a 'wildcard'. In case you haven't heard of them, they do basicly exactly what you want. In your case it would take the '.' and match the rest of the letters, allowing the place where the period is too be any letter. Java has support for this by the looks of it. Try Google. I can't give ya much else on this, but you also might want to consider looking into Regular expressions.

Jun 6th, 2006, 9:34 PM	#3
larry Newbie Join Date: Jun 2006 Posts: 3 Rep Power: 0	yeah I know it has a Pattern and Matcher class. Pattern pat = Pattern.compile(find); //need to put pattern here Matcher m = pat.matcher(tarray[2]); if(m.find()) I'm trying to let the user enter in a name and have it match against tarray[2]. I'd prefer if the user could enter jo.n smi.h and have the matcher find it. I'm hoping someone that knows regular expressions can help me out.

Jun 6th, 2006, 11:42 PM	#5
larry Newbie Join Date: Jun 2006 Posts: 3 Rep Power: 0	I really appreciate your help. The code examples are helping me. Your example is very close and I think I am getting somewhere with it. Thank you. I have a String named find that contains a name passed from the user. I need to compare it to a name in a file, which is tarray[2]. I am trying to find a way so the user can enter in let's say jo.n smi.h and it compares it to tarray[2]. If it doesn't match it goes to the next record. Maybe even john sm*. My initial code just compared two strings, but that wasn't good enough because they had to match exactly. I appreciate evreyone's help. Thank you.

Jun 7th, 2006, 12:11 AM	#6
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 908 Rep Power: 3	I would recommend first removing all non-alphanumeric characters (excepting "."), then replacing any occurences of "." with "*". That way any occurences of "." in the input text will match anything, so "jo.n sm.th" will match "john smith", "jonathan epsilon smoog tooth", etc. If that's not what you're looking for, you'll have to be more specific about exactly what you want to match.

Jun 7th, 2006, 12:23 PM	#7
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 908 Rep Power: 3	Small correction to my last post: "." should become ".", not "".

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Programming Forums > Application Development > Java

need pattern matching help