Data Types in Java
Table of Contents
Introduction
In computer science, data is grouped according to type. This chapter covers the naming conventions used for data types in Java.
Java is a statically typed programming language, meaning that what kind of data it is is as important as the data itself. In Java, when creating an array, declaring a variable, or making a function, you must declare the type before its name.
Numbers
Integer
Integers in computer science refer to whole numbers.
100 - an integer
How to declare an integer in Java:
int x = 100;
Double
Doubles refer to numbers fixed to a point. Example: Decimal numbers
1.50 - a double
How to declare a double in Java:
double y = 1.50;
Operands
Operands are symbols signifying a specific mathematical operation to be performed.
In this example, the operand + tells us to add the numbers 1 and 2 together:
1 + 2
Some common operands:
+ - addition of numbers, and concatenation of Strings
- - subtraction of numbers
/ - division of numbers
* - multiplication of numbers
= - assigns a value. The value item on the left side becomes the value of the item on the right side.
== - strict equality. The value of the item on the left must be the same as the value of the item on the right side.
% - pronounced "modulo". Determines the remainder of dividing two numbers.
Booleans
Booleans refer to items that evaluate to either true or false.
How to declare a boolean in Java:
boolean sorted = false;
Characters
A character refers to a single symbol between ''. Notice the single quotation marks.
Examples of characters:
'a'
'@'
'1'
How to declare a character in Java:
char letter = 'a';
Strings
A String refers to a series of characters between "". It is most frequently used for holding text.
Examples of Strings:
"abcde"
"The quick brown fox jumps over the lazy brown dog"
"12345678"
How to declare a string in Java:
String talk = "blah blah blah";