Learning Java

Data Structure:

A way of maintaining, changing, manipulating data in Java.

Arrays

A DS allows you to store more variables Define size Cannot expand the size of an array

List

If you want to expand the size, you can use Lists

Sets

Similar to list, does not allow duplicates. And order is not guaranteed

Stacks

Stacks are LIFO: Last in First out

Queues

Queues are FIFO: First in First out

Representing Money : Use BigDecimal

Double type has certain precision, you can lose some data. To represent money, use the big decimal data type.

Null Values - Using Optionals

null value cannot be bound to a "var" keyword or any other Primitive data type. Use the object data type.

Exceptions - Checked Exceptions and Unchecked Exceptions

Checked Exceptions - Exceptions that need to be handled at Compile time. Use try-catch block or throws keyword

Unchecked Exceptions - Not checked at Compile time, if you handle them, the program will not give you a compilation error

Keywords need to learn for try-catch

try : add logic here, if that logic errs, use catch

catch : In here you pass the exception type you are expecting, if you do not know what exception type, put "Exception"

finally : If the try-catch works or not, execute regardless, for cleanup purposes

catch () : Inside this paranthesis, it is not limited by one exception, you can have multiple catch () blocks, or have one catch () with multiple exceptions separated by "|"

Define your own exceptions