Variables are one of the most important concepts in computer programming. They store information such as letters, numbers, words, sentences, true/false, and more. This will give you an introduction into using variables in Java. It is not intended as a complete guide, but as a stepping stone into the world of the computer programmer.

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[edit] Steps

Create a simple Java program. An example is provided called Hello.java :

public class Hello {
  public static void main(String[] args) {
  System.out.println("Hello World!");
}}

Scroll to a place where you want to insert the variable. Remember: If you place a variable in the main class, you can reference it anywhere.
Choose the type of variable you need:
- int -- Stores a whole number
- double -- Stores a decimal
- float -- Stores a floating point number
- boolean -- Stores a true/false value
- String -- Stores a collection of characters. Note that this type name starts with a capital letter
- char -- Stores a single character
Create the variable. Here are examples of how to create and assign a value to each type.
- int someNumber = 0;
- double someDouble = 635.29;
- float someDecimal = 4.43f;
- boolean trueFalse = true;
- String someSentence = "My dog ate a toy";
- char someChar = 'f';
Understand how this works. It is basically "type name = value".
Protect variables from being edited later, optionally, by adding "final type name" between the parentheses in the second line of your code (public static void main).
- final int someNumber = 35; Adding the 'final' here means that the variable 'someNumber' cannot be changed later