Reference type variables are object instances of classes. Below, you will see examples of variable initializations for each of these types: The most commonly used variable types in learning programming are int, double, char and boolean. Primitive type variables store the value in the variables memory location. The other types are valid Java types and can be used to better manage the storage footprint of your program. Note: the variable types in bold are the ones that we will focus on in this course. So, a reference variable stores a 'reference' to another memory location where the information is stored. Reference type variables are user created and thus, do not have a pre-defined size that the computer is aware of. The value of a primitive variable is stored right in the allotted space. Primitive type variables are native to Java and have a pre-defined size. When a variable is declared a space for it is created in the computer's memory and labeled with the variable name. The two main types of variables are primitive and reference. This can happen anytime after the declaration (lines 1 and 2) OR at the same time as the declaration (line 3). The first time we assign a value to a variable it is called initializing the variable (initialization). For all numeric and boolean type variables, no quotes are utilized (line 1).

For char type variables, we surround the character in single quotes (line 2). When assigning String values, we surround the string in double quotes (line 3).

Modulus (%) is an operation that gives the remainder when two values are divided. Variables can be assigned to literals (programmer defined values), input results, or computations.īasic computation operators include +, -, *, /, and %. When assigning a variable, the variable goes on the left, followed by an equals sign (=), and the value on the right. The process of assigning a variable is to give it a value. Variable declarations can happen on different lines (lines 1 and 2), or on the same line if they are the same type (line 3). The process of declaring a variable is giving it a type and a name. It is a convention in Java to name variables beginning with lower case letters and using capitalization to enhance readability (camelCase).Variable names cannot be reserved words (e.g.Variable names can only contains letters, numbers and underscores.The variable name must begin with a letter.Also, when naming a variable in Java the following rules apply: For example, itemCost is much more descriptive than x. When naming variables, programmers should choose names that indicate the value that the variable holds. There are two main types of variables: primitive and reference. Variables in Java are used to store information that may change through the course of the program, either through computation or user input.

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