Update Pangram.java using Java Collections

[Ankit-Saha08]

A simple separate function isPangramOrNot(String s) has been created which implements the Pangram checking of a string using Java Collection Framework approach.

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.

[Ankit-Saha08]

I request the maintainer(s) to merge my request using "hacktoberfest-accepted" label.

[debasishbsws]

Looks like you haven't add test for your function. (It is always better to add test you know)
https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/PangramTest.java
Add some test for you method too. you can use the same example just with your method call.
and isPangramUsingSet(String s) is a better name.

BTW thanks for contributing.

[Ankit-Saha08]

Ok, I will update the method name isPangramUsingSet(String s) and also add some tests for my method.

[Ankit-Saha08]

Hi, I have updated the function name to isPangramUsingSet(String s) and also added tests for my function.

P.S. - I would be grateful if my contribution is accepted and merged using "hacktoberfest-accepted" label.

[debasishbsws]

Add the test in this barnch.

[Ankit-Saha08]

Hii, I have updated the test cases in PangramTest.java file in this current PR branch itself.

P.S. - Looking forward to having my contribution merged and accepted.

[debasishbsws]

Looks Good. Thanks