What is the difference between a regular expression and a pattern in Java?

In Java, a regular expression (regex) is a sequence of characters that defines a search pattern. It is used to match and manipulate text. In contrast, a pattern in Java is a description of a set of matching strings.

While regular expressions and patterns may seem similar, they have some key differences. One major difference is that patterns are compiled into objects that can be reused, while regular expressions are not.

Patterns can also be used for more complex matching than regular expressions. For example, patterns can specify a set of alternative characters to match, and can match whole words or lines of text. Regular expressions, on the other hand, are better suited for simple matching tasks.

Overall, the choice between regular expressions and patterns in Java depends on the specific task at hand. Regular expressions are best for simple tasks, while patterns are better suited for more complex tasks that require reusable objects.