Intro Primitive Types Reference Types Stack and Heap Code Example Quiz

Unit 1 - Reference Types

An overview of Reference Types

• 1 min read

Refrence Types

Reference types in Java include classes, arrays, and interfaces. Unlike primitive types, reference types store addresses (references) to objects rather than the objects themselves.

Classes

  • Create complex data structures by grouping variables and methods.

Example:

class Person {
    String name;
    int age;
}
Person person = new Person(); // `person` reference in stack, `Person` object in heap

Arrays

  • Collections of variables of the same type.

Example:

int[] numbers = new int[5]; // `numbers` reference in stack, array in heap

Popcorn Hack

public class Main {
    public static void main(String[] args) {
        // Create a reference type variable of type String
        // ______ myString = "Hello, World!";
        String myString = "Hello, World!";
        
        // Create a reference type variable of type Array
        int[] myArray = new int[] {1, 2, 3, 4, 5};

        // Print the values
        System.out.println(myString);
        System.out.println(Arrays.toString(myArray));
    }
}

Main.main(null);

Hello, World!
[1, 2, 3, 4, 5]