Write a method that takes two string parameters, and tells whether the first is a substring of the second. You can't use

[answerhappygod]

Write a method that takes two string parameters, and tells
whether the first is a substring of the second. You can't use
framework methods that do this for you, such as indexOf(). In other
words, you have to write the loops yourself. But, you can use the
primitive methods such as charAt().
Also analyze the program's performance and state the big-O
complexity of your method.
Provide a screenshot of the code working.