How Can I Implement a SQL LIKE Operator Using Regular Expressions in Java?

Implementing a SQL-Style LIKE Operator in Java

SQL's LIKE operator is a powerful tool for pattern matching in queries. It allows for flexible searches based on a given string template. To replicate this functionality in Java, one can leverage regular expressions.

Consider the following example:

myComparator.like("digital","%ital%");
myComparator.like("digital","%gi?a%");
myComparator.like("digital","digi%");

These should evaluate to true because the text matches or partially matches the given templates. Conversely, the following should evaluate to false:

myComparator.like("digital","%cam%");
myComparator.like("digital","tal%");

To implement such a comparator using regular expressions, we can follow the rules below:

• The .* wildcard will match any sequence of characters.
• The ? wildcard will match any single character.
• To escape a literal period (.), use ..

For instance, to check if "digital" matches the template "%ital%", we can use:

"digital".matches(".*ital.*");

Similarly, we can use .*gi.a.* and digi.* for the other true cases. For the false cases, we can use �m% and tal%.

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