Java Variables and Operators: Everything You Need to Know

What Are Variables in Java?

Variables are containers that hold data values. Each variable in Java has a specific type, which determines the kind of data it can store and the operations you can perform on it.

Declaring Variables

To declare a variable, specify its data type followed by its name:

int age;

You can also assign a value during declaration:

int age = 25;

Variable Types in Java

1. Local Variables: Declared within a method and accessible only inside it.

2. Instance Variables: Declared inside a class but outside any method. These belong to an object.

3. Static Variables: Declared with the static keyword and shared among all objects of a class.

Example:

public class Person {

static String species = "Human"; // Static variable

int age; // Instance variable

public void setAge(int newAge) {

int ageDifference = newAge - age; // Local variable

age = newAge;

System.out.println("Age updated by " + ageDifference + " years."); } }

Java Operators

Operators are symbols used to perform operations on variables and values. Java provides a rich set of operators categorized as follows:

1. Arithmetic Operators

Used to perform basic mathematical operations.

Example:

int a = 10, b = 3; System.out.println("Addition: " + (a + b)); System.out.println("Division: " + (a / b)); System.out.println("Remainder: " + (a % b));

2. Assignment Operators

Used to assign values to variables.

Example:

int a = 5; a += 3; // a = a + 3 System.out.println(a); // Output: 8

3. Relational Operators

Used to compare two values and return a boolean result.

Example:

int a = 10, b = 20; System.out.println(a < b); // Output: true

4. Logical Operators

Used to perform logical operations on boolean values.

Example:

boolean a = true, b = false; System.out.println(a && b); // Output: false System.out.println(a || b); // Output: true

5. Increment and Decrement Operators

Used to increase or decrease the value of a variable by 1.

Example:

int a = 5; a++; // a becomes 6 a--; // a becomes 5 again

6. Bitwise Operators

Used to perform bit-level operations.

Combining Variables and Operators: A Practical Example

Let’s create a program that calculates the total price of items in a shopping cart.

public class ShoppingCart {

public static void main(String[] args) {

int item1Price = 50;

int item2Price = 30;

int item3Price = 20;

int total = item1Price + item2Price + item3Price;

double discount = 0.1; // 10% discount

double finalPrice = total - (total * discount);

System.out.println("Total Price: " + total);

System.out.println("Final Price after Discount: " + finalPrice); } }

Conclusion

Java variables and operators are the building blocks of any program. Understanding their usage and potential will help you write efficient and powerful code. Experiment with the examples provided to solidify your learning.

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