Arraylist/Exceptions/Files

Characteristics of ArrayList?

• Grows automatically

• Shifts when removing elements

• Can have elements of multiple types

• No primitive types as type ArrayList use wrapper methods

What is a set?

• its a list that doesn’t allow duplicates

• doesn’t preserve order

• has no index methods

What is a map?

A list that stores key - value pairs

Keys are uniqe

Value can be duplicated

Iterator hasNext()

checks if a another elements is available

Iterator Next()

returns the next element

What is the fail fast aspect?

Once iterator created expects the collection to remain unchanged, after modification iterator becomes invalid

What is an exception?

An exception is an event that occurs at runtime and interrupts the normal execution of a program.

How do you write an exception handler

Using a try catch block

Key aspect of nested try catch blocks?

If the inner catch can’t handle the error, java checks the outer block

What does the finally block do?

Performs operations whether or not an exception occurs.

What is the characteristic of Checked Exceptions?

They are required by the compiler to be caught using a try except block / declared using throws

What is the characteristic of Unchecked Exceptions?

They are not required by the compiler to be caught using a try except block / declared using throws