CODEWITHSUNDEEP
javaregex
Mondin Francisco Alegrid
Mondin Francisco Alegrid

Reputation: 119

Need help about detecting license plate numbers using Android Pattern

I need to find a license plate number in a text matching a pattern like this below ("L" stands for a letter,"D" stands for a number):

LLLDDD,LLLDDDD,LLDDDD,DDDDLL

there can be spaces between them like LLL DDD

I have this method that works fine if the text is just the license plate number like for example "SS1234"

public static boolean plateNumberExist(String target) {
    return Pattern.compile("^([A-Za-z]{3} ?[0-9]{3})?([A-Za-z]{3} ?[0-9]{4})?([A-Za-z]{2} ?[0-9]{4})?([0-9]{4} ?[A-Za-z]{2})?$").matcher(target).matches();
}

But if i add another text with the license plate number like the code below then its always false

if(plateNumberExist("Republic SS1234")){
    showToast("Plate Number Found");
}else{
    showToast("No Plate Number");
}

So the actual code that i am using to get the license plate number is the code below but it also doesn't work.

String inputString = "Republic SS1234";
Pattern pattern = Pattern.compile("^([A-Za-z]{3} ?[0-9]{3})?([A-Za-z]{3} ?[0-9]{4})?([A-Za-z]{2} ?[0-9]{4})?([0-9]{4} ?[A-Za-z]{2})?$");
Matcher matcher = pattern.matcher(inputString);
if (matcher.find()) {
   String platenumber = inputString.substring(matcher.start(), matcher.end());
                showToast(platenumber);
            } else {
                showToast("No Plate Number Found");
            }

The problem is with the regex but i just don't understand why it works if its only a license plate number but if i have other text with the license plate number it doesn't work

Upvotes: 2

Views: 334

Answers (1)

rustyx
rustyx

Reputation: 85371

The ^ and $ regex symbols denote the beginning and end of the input, respectively.

Replace those with \\b (beginning/end of a word), and it should work.

Live demo

== Edit ==

Note that your regex itself can be simplified and you should use a loop if you want to collect all matches. Have a look:

String inputString = "Republic SS1234 and ABC 1234";
Pattern pattern = Pattern.compile(
    "(?i)\\b([A-Z]{3} ?[0-9]{3,4}|[A-Z]{2} ?[0-9]{4}|[0-9]{4} ?[A-Z]{2})\\b");
Matcher matcher = pattern.matcher(inputString);
while (matcher.find()) {
    String platenumber = matcher.group(1);
    . . .
}

(?i) means ignore-case, {3,4} means "from 3 to 4" and | means "or"

Upvotes: 4

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