This video is Part 1 of 2 series which teaches how to create a standard template which can be used for any String program which requires character level manipulation.
Similarly there is another video which covers all String program which require word level manipulation.

For program on String in Java click on -https://simplycoding.in/string-handling-programs/
For program on character pattern in Java click on - https://simplycoding.in/solve-any-character-pattern-program-in-java/