AP CSA Unit 1: Lesson 3 - Data Types

primtive

int, double, boolean

reference

String

data types

it's very important to tell the computer what kind of input you're going to give it, so it knows how to deal with the data

type

tells Java two things:
What possible values can be stored - this is called a domain and is important as Java needs to know how big of a box in memory to allocate for the input.
What operations can be performed on the data - for example can two variables of this type be added together?

int

used for storing an integer value. ints are pretty small in memory

double

used for storing a decimal value (a number which is not an integer). doubles take up more space than ints because of the decimal component

boolean

used for storing a true or false value, in memory this value can be represented by a single bit of memory, stored as a 1 or 0

Strings = reference data type

take up lots of space in memory because they have to store each individual character separately

Input Mismatch Exception = runtime error

the code will still compile

literal

a value in Java which is a direct representation of the data

final

used to avoid having to keep typing it you can use a variable to store its value