正则表达式匹配2个或更多逗号

Question

I'm trying to write a regex that will identify whether a string has 2 or more consecutive commas. For example:

hello,,457
,,,,,
dog,,,elephant,,,,,

Can anyone help on what a valid regex would be?

Answer 1

String str ="hello,,,457";
Pattern pat = Pattern.compile("[,]{2,}");
Matcher matcher = pat.matcher(str);
if(matcher.find()){
    System.out.println("contains 2 or more commas");
}

Answer 2

The below regex would matches the strings which has two or more consecutive commas,

^.*?,,+.*$ 

DEMO

You don't need to include start and the end anchors while using the regex with matches method.

System.out.println("dog,,,elephant,,,,,".matches(".*?,,+.*"));

Output:

true

Answer 3

Try:

int occurance = StringUtils.countOccurrencesOf("dog,,,elephant,,,,,", ",,");

or

int count = StringUtils.countMatches("dog,,,elephant,,,,,", ",,");

depend which library you use: Check the solution here: Java: How do I count the number of occurrences of a char in a String?