Java Variables

A variable stores a value. In Java you must say what type of value it holds. The common types are int (whole numbers), double (decimals), boolean (true or false), char (one character) and String (text).

ExampleJava

public class Main {
  public static void main(String[] args) {
    String name = "Ada";
    int age = 36;
    double height = 1.68;
    boolean student = false;
    System.out.println(name + " is " + age + " years old.");
    System.out.println("Height: " + height + ", student: " + student);

    age = 37;          // change the value
    final int YEAR = 2026;  // final: cannot be changed
    System.out.println("Next year: " + age + " in " + YEAR);
  }
}

Output

Ada is 36 years old.
Height: 1.68, student: false
Next year: 37 in 2026

final makes a variable a constant. You can also let Java work out the type with var: var count = 10; is an int.

Quick check

Which type stores whole numbers?

doubleStringint

Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.

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