Java Data Types

Java is a statically typed language, meaning every variable must be declared with a data type. Data types define the kind of data a variable can hold.

🔰 Categories of Data Types

Java data types are divided into two main categories:

1. Primitive Data Types
2. Non-Primitive (Reference) Data Types

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🧱 1. Primitive Data Types

Java has 8 built-in (primitive) data types:

Data Type	Size	Description	Example
byte	1 byte	Stores whole numbers from -128 to 127	byte b = 100;
short	2 bytes	Stores whole numbers from -32,768 to 32,767	short s = 30000;
int	4 bytes	Stores whole numbers from -2^31 to 2^31-1	int i = 500000;
long	8 bytes	Stores very large whole numbers	long l = 10000000000L;
float	4 bytes	Stores fractional numbers (6-7 decimal digits)	float f = 5.75f;
double	8 bytes	Stores fractional numbers (15 decimal digits)	double d = 19.99;
boolean	1 bit	Stores true or false values	boolean isJavaFun = true;
char	2 bytes	Stores a single character	char grade = 'A';

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🧭 2. Non-Primitive (Reference) Data Types

These refer to objects and include:

• Strings
• Arrays
• Classes
• Interfaces

String name = "InitCareer";
int[] numbers = {1, 2, 3};

Non-primitive types are created by the programmer and have methods associated with them.

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🚀 Real World Example

Think of primitive types as basic ingredients like rice, sugar, and salt. Non-primitive types are like recipes you create using those ingredients.

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🧠 Explain Like I'm Five

Primitive types are like LEGO blocks. Each one is a fixed shape and color. You can combine them to build something bigger (non-primitive types), like a LEGO house or car.

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💡 Fun Fact

Java's primitive types are not objects, which makes them faster for computation—great for performance-critical applications like games or real-time systems.

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🧪 Exercise

1. Declare a variable of each primitive type.
2. Print their default values.
3. Create a String and an array, then print them.

public class DataTypesExample {
    public static void main(String[] args) {
        byte b = 10;
        short s = 1000;
        int i = 100000;
        long l = 10000000000L;
        float f = 5.75f;
        double d = 19.99;
        boolean bool = true;
        char c = 'A';

        String name = "InitCareer";
        int[] numbers = {1, 2, 3};

        System.out.println("Byte: " + b);
        System.out.println("Short: " + s);
        System.out.println("Int: " + i);
        System.out.println("Long: " + l);
        System.out.println("Float: " + f);
        System.out.println("Double: " + d);
        System.out.println("Boolean: " + bool);
        System.out.println("Char: " + c);
        System.out.println("String: " + name);
        System.out.println("Array element: " + numbers[0]);
    }
}