if(str.matches("(.)*\\d(.)*")){ containsNumberList.add(str); }

This code checks if the string "str" contains any digit(s) and adds it to a list called "containsNumberList" if it does. The regular expression used in the "matches" method checks if the string contains any character (".") followed by a digit ("\\d") and then any character again (".)*"). The backslashes in "\\d" are used to escape the "d" character and indicate that we are looking for a digit, not the character "d" itself.