Can we use regex in substring?

You can use contains(), indexOf() and lastIndexOf() method to check if one String contains another String in Java or not. If a String contains another String then it’s known as a substring. The indexOf() method accepts a String and returns the starting position of the string if it exists, otherwise, it will return -1.

The reason is, that first the Java compiler interprets the two \\ characters as an escaped Java String character . After the Java compiler is done, only one \ is left, as \\ means the character \ . The string thus looks like this: \.5 Mar 2019

REGEXP_SUBSTR extends the functionality of the SUBSTR function by letting you search a string for a regular expression pattern . It is also similar to REGEXP_INSTR , but instead of returning the position of the substring, it returns the substring itself.