ICS3U-Variables

A variable is a symbolic name for a location in memory used to store data. The value stored in a variable can be modified and read during the execution of the Java program. To use a variable in a Java, it must be first be created. Creating a variable in Java is done by stating the variable type and by giving it an identifier (the variable name).

Three sections are necessary for creating variables in Java:

Example: to create a variable in Java with the variable name {identifier} of "max" :

int max;

You can create many variables of the same type at once, for example:

int max, min;

Rules for variable names:

1. Variable names are made up from a series of Unicode characters that begins with a letter (no spaces or punctuation).
2. Some words, called "keywords" are reserved by Java (they are part of the Java language) and you may not use them as variable names. These are keywords used by the compiler to control your program. For a list see:keywords.
3. It must be unique within its scope. A variable may have the same name as a variable whose declaration appears in a different scope. In some situations, a variable may share the same name as another variable if it is declared within a nested block of code.
4. Good variable names tell you what the variables are for; using good names makes it easier to understand the flow of your program.
5. JAVA is case-sensitive! This means that UPPERCASE and lowercase letters are considered to be different. A variable named me is different from ME, which is different from Me and mE.

NOTE: It is important to initialize a variable (set it to some value) before you use it in a calculation or print it. If you do not initialize the variable, Java will cause a compile error.