My Little World

Today, I visit my wordpress blog: julyhoping.wordpress.com

It’s my 1st wordpress blog, before I moved to this site. I created it in my 2nd year at university. Reading it again made me remember the past – the time I was really interested in programming and the time I began my study at APCS. I missed all those memories!

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Hehe, here is my “own” definition for bonds, stocks, etc.

- Zero-coupon bond: like a bank account. Buy this type of bond is similar to deposit money to bank account and earn interest. However, with a same interest, deposit $100 in a bank account means that you need to pay total $100 for a bank while a zero-coupon with face value of $100 can be bought by a lower price. So investing in bonds make more profit than send money to a bank. Instead you have a lot of money, then you should ask a bank to keep them for you and earn interest. Otherwise, take the money you have to invest to make more and more money

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• package: group similar classes together. Classes in the same package share “public” method & attribute.
• interface: just use to define prototype for common classes, not concern about implementation. Classes can inherit (using keyword “implements”) from many interface.
• abstract class: (faster than interface since interface need to look up which implement to use) classes can inherit (using keyword “extends”) from only 1 abstract class. Abstract class cannot be instantiated.
• abstract method: a method is declared without definition/implementation.
• static final: attribute defined by using both keywords “static” and “final” are not absolutely constant, but it’s an instance stored at the same memory address. Its value can be changed by using reference assignment.
• final class:
• final method:
• static:
• inheritance: if inherited class call “super” method, then if it override a method of parent class, then “super” use this override method instead of the method of parent class.

1. Username Regular Expression Pattern:

^[a-z0-9_-]{3,15}$

2. Password Regular Expression Pattern:

((?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{6,20})