Difference between regular expression operators in JAPE ( Java Annotation Patterns Engine)

I would like to know the difference between these pair of regular expressions in Java Annotation Patterns Engine (JAPE).

Between ==~ and =~
Between !~ and !=~

As for the difference between == and =~ I have learnt that == is for complete string matching while =~ is to match a regular expression instead of a string. But when I used ==~ in place of =~ the result was the same. So kindly explain to me the difference with examples.

Thanks

Solution

With =~ and !~, the pattern can match any substring of the string being tested. In most regex implementations, this is the default behaviour.

==~ and !=~ are for whole-string matching. Typically, the same can be achieved by having the pattern start with ^ and end with $.

Example:

myString =~ "[AB]" returns true if myString contains at least one A or B
myString ==~ "[AB]" returns true if myString is exactly "A" or "B"
myString !~ "[AB]" returns true if myString contains no A and no B
myString !=~ "[AB]" returns true for any myString that is not exactly "A" and not exactly "B"