Data Types in Java - Primitive & Reference Types Explained

Introduction

Data types in Java define what kind of values a variable can hold. Understanding data types is crucial for writing correct and efficient Java programs.

Primitive Data Types

Java has 8 primitive data types divided into 4 categories:

Integer Types

public class IntegerTypes {
    public static void main(String[] args) {
        byte b = 100;
        short s = 10000;
        int i = 100000;
        long l = 10000000000L; // Note the L suffix
        
        System.out.println("byte: " + b);
        System.out.println("short: " + s);
        System.out.println("int: " + i);
        System.out.println("long: " + l);
    }
}

Floating-Point Types

public class FloatingTypes {
    public static void main(String[] args) {
        float price = 99.99f; // Note the f suffix
        double pi = 3.14159265358979;
        
        System.out.println("Price: " + price);
        System.out.println("PI: " + pi);
    }
}

Character Type

public class CharType {
    public static void main(String[] args) {
        char letter = 'A';
        char unicode = '\u0041'; // Also 'A'
        char number = 65; // Also 'A' (ASCII value)
        
        System.out.println(letter);
        System.out.println(unicode);
        System.out.println(number);
    }
}

Boolean Type

public class BooleanType {
    public static void main(String[] args) {
        boolean isJavaFun = true;
        boolean isFishTasty = false;
        
        System.out.println("Is Java fun? " + isJavaFun);
        System.out.println("Is fish tasty? " + isFishTasty);
    }
}

Reference Types

Reference types hold references to objects rather than the actual values.

String

String name = "JavaCompiler.in";
String greeting = new String("Hello");

Arrays

int[] numbers = {1, 2, 3, 4, 5};
String[] names = new String[3];

Objects

Student student = new Student();

Summary

• Java has 8 primitive types for basic values
• Reference types hold object references
• Choose the right type for your data needs
• Use int for most integer operations, double for decimals