What is the difference between static and dynamic variable in java

Gladys 124 Published: 11/09/2024

What is the difference between static and dynamic variable in java

I'd be happy to explain the difference between static and dynamic variables in Java!

Static Variables

In Java, a static variable is a variable that belongs to the class itself, rather than to an instance of the class. When you define a static variable inside a class, it's essentially shared among all instances of the class.

Here are some key characteristics of static variables:

Shared among instances: Static variables are shared by all instances of the same class. No instance required: You don't need an instance of the class to access a static variable. Class-level scope: Static variables have class-level scope, meaning they can be accessed directly from the class name.

For example:

public class MyClass {

public static int myStaticVariable = 0;


}


MyClass.myStaticVariable = 5; // This is valid!


MyClass obj1 = new MyClass();


obj1.myStaticVariable = 10; // This will not work, as you can't assign a value to a static variable from an instance

Dynamic Variables (Instance Variables)

In Java, dynamic variables, also known as instance variables or non-static variables, are variables that belong to individual instances of a class. Each instance has its own separate copy of the variable.

Here are some key characteristics of dynamic variables:

Belong to an instance: Dynamic variables belong to a specific instance of a class. Instance required: You need an instance of the class to access and manipulate dynamic variables. Scope limited to instance: Dynamic variables have scope limited to the instance they belong to, and you can't access them directly from the class name.

For example:

public class MyClass {

public int myDynamicVariable;


public MyClass() {


myDynamicVariable = 0;


}


}


MyClass obj1 = new MyClass();


obj1.myDynamicVariable = 5; // This is valid!


MyClass obj2 = new MyClass();


System.out.println(obj2.myDynamicVariable); // Outputs: 0 (not modified)


// If you try to access a dynamic variable from the class name, you'll get an error


// MyClass.myDynamicVariable = 10; // This will not work!

Key differences

Here are some key differences between static and dynamic variables:

Scope: Static variables have class-level scope, while dynamic variables have instance-level scope. Access: You can access a static variable directly from the class name, but you need an instance of the class to access a dynamic variable. Sharing: Static variables are shared among all instances of the same class, while dynamic variables belong to individual instances and don't share values.

In summary, use static variables when you want to maintain class-level state that's shared among all instances. Use dynamic variables (instance variables) when you need to keep track of instance-specific data.

What are the main variables in java with examples w3schools

I'm happy to help!

In Java, a variable is a storage location that holds a value of a specific type. The main variables in Java are:

Primitive Variables: These are basic data types that are built into the language.

Example:

int age = 25; // integer variable

double height = 5.8; // double variable


boolean isAdmin = true; // boolean variable
Reference Variables (Objects): These store a reference to an object of a specific class.

Example:

String name = "John"; // string object

Car myCar = new Car("Toyota", 2015); // car object


Person person = new Person("Jane"); // person object
Array Variables: These are used to store a fixed-size, homogeneous collection of values.

Example:

int[] scores = {90, 80, 70}; // integer array

String[] names = {"John", "Mary", "David"}; // string array
ArrayList Variables (Collections): These are used to store a dynamic-size, heterogeneous collection of objects.

Example:

List countries = new ArrayList<>();

countries.add("USA");


countries.add("Canada");


countries.add("Mexico");


List numbers = new ArrayList<>();


numbers.add(1);


numbers.add(2);


numbers.add(3);

In summary, the main variables in Java are:

Primitive Variables: int, double, boolean, etc. Reference Variables (Objects): String, Car, Person, etc. Array Variables: int[], String[], etc. ArrayList Variables (Collections): List<String>, List<Integer>, etc.

Please visit W3Schools for more information on Java variables and data types: https://www.w3schools.com/java/

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