Java Program to Display Size of Different Data Types

Problem Description

Write a Java program to display the size of various primitive data types like int, float, double, char, etc.

Code

public class DataTypeSizes {
    public static void main(String[] args) {
        System.out.println("Size of int: " + (Integer.SIZE / 8) + " bytes.");
        System.out.println("Size of long: " + (Long.SIZE / 8) + " bytes.");
        System.out.println("Size of char: " + (Character.SIZE / 8) + " bytes.");
        System.out.println("Size of float: " + (Float.SIZE / 8) + " bytes.");
        System.out.println("Size of double: " + (Double.SIZE / 8) + " bytes.");
        System.out.println("Size of short: " + (Short.SIZE / 8) + " bytes.");
        System.out.println("Size of byte: " + (Byte.SIZE / 8) + " bytes.");
    }
}

Output

Size of int: 4 bytes.
Size of long: 8 bytes.
Size of char: 2 bytes.
Size of float: 4 bytes.
Size of double: 8 bytes.
Size of short: 2 bytes.
Size of byte: 1 bytes.

Explanation

1. Wrapper Classes: Java provides wrapper classes for primitive types (e.g., Integer for int, Double for double).
2. SIZE Constant: These wrapper classes have a constant SIZE which holds the size of the type in bits.
3. Calculation: Dividing the size in bits by 8 gives the size in bytes.

Try Yourself

1. Bits: Modify the program to print the size in bits instead of bytes.
2. Range: Can you print the minimum and maximum values for int? Hint: Use Integer.MIN_VALUE and Integer.MAX_VALUE.
3. Boolean: Try to find Boolean.SIZE. Does it exist? Why or why not?
4. String: Can you find the size of a String? (Hint: It's not a primitive type).
5. Brain Twister: If short is 2 bytes (16 bits), calculate its maximum positive value manually ($2^15 - 1$). Does it match Short.MAX_VALUE?