Data Types

Java data types can mainly be split into Primitive Types and Reference Types. Primitive types store the value directly, while reference types point to an object/location. The first thing beginners should know is that getting the data type right is what makes the operations on it work correctly. For example, if you're not going to do math with a phone number, storing it as a String makes a lot more sense.

public class Main {
  public static void main(String[] args) {
    int quantity = 3;
    double price = 19.99;
    char grade = 'A';
    boolean isAvailable = true;
    String productName = "Keyboard";

    System.out.println(productName + " x " + quantity);
    System.out.println("Total: " + (quantity * price));
    System.out.println("Grade: " + grade);
    System.out.println("Available: " + isAvailable);
  }
}

In this example, data for something like a product order is stored using several different types. quantity * price multiplies two numeric types together to get the total price.

Keyboard x 3 Total: 59.97 Grade: A Available: true