Variables & Types

Variables and Primitive Types

Java is statically typed — every variable has a declared type:

int age = 25;           // 32-bit integer
long population = 8_000_000_000L;  // 64-bit integer
double pi = 3.14159;    // 64-bit floating point
boolean active = true;  // true or false
char grade = 'A';       // single character

String

String is a class (not a primitive), but behaves like one for most purposes:

String name = "Alice";
String greeting = "Hello, " + name + "!";  // concatenation

Type Inference with var

Since Java 10, you can use var to let the compiler infer the type:

var score = 100;        // inferred as int
var message = "Hi";    // inferred as String

var is most useful when the type is obvious from the right-hand side or when the full type name is long and repetitive (e.g., var users = new ArrayList<String>() instead of ArrayList<String> users = new ArrayList<>()). Avoid var when the type isn't clear from context — explicit types make code easier to read. Note that var can only be used for local variables, not for fields, method parameters, or return types.

Constants

Use final to declare a constant:

final double TAX_RATE = 0.08;

Your Task

Declare the following variables and print the output exactly as shown:

• name = "Alice", age = 25, height = 1.75, student = true
• Print: Alice is 25 years old
• Print: Height: 1.75
• Print: Student: true