Variables
Variables are used whenever there’s a need to store a piece of data. A variable contains data that can be used in the program elsewhere. Using variables also ensures code re-usability since it can be used to replace the same value in multiple places.
Declaring a Variable
To declare a variable in Java, any of these three keywords can be used along with a variable name:
- The data type.
- The variable name.
- The value.
int age = 28;char grade = 'A';boolean late = true;byte b = 20;long num1 = 1234567;short no = 10;float k = (float)12.5;double pi = 3.14;
The equal sign =
is used to assign a value to a variable. After the initial assignment is made, the value of a variable can be updated to new values as needed.
Types of Variables
In Java, there are three types of variables that can be used and each of them serves a different purpose. These types are discussed below one-by-one.
1. Local Variables
Local variables are the ones that are declared within a method or a block of code and are only accessible within that scope:
void exampleMethod() {int localVar = 5;// localVar is only available within .exampleMethod()}
2. Instance Variables
Instance variables are the ones that are declared within a class but outside the scope of a method. Each instance of the class includes a unique version of the variable:
public class MyClass {int instanceVar = 10;// Each instance of MyClass has its own instanceVar}
3. Static Variables
Static variables are the ones that belong to a class rather than its instances. In the case of these variables, only one copy is created in a class and distributed among all instances of that particular class:
public class SharedClass {static int staticVar = 100;// All instances of SharedClass share the same staticVar}
Contribute to Docs
- Learn more about how to get involved.
- Edit this page on GitHub to fix an error or make an improvement.
- Submit feedback to let us know how we can improve Docs.
Learn Java on Codecademy
- Career path
Computer Science
Looking for an introduction to the theory behind programming? Master Python while learning data structures, algorithms, and more!Includes 6 CoursesWith Professional CertificationBeginner Friendly75 hours - Free course
Learn Java
Learn to code in Java — a robust programming language used to create software, web and mobile apps, and more.Beginner Friendly17 hours