This program prints sizes in bytes of primitive types in java.

sizes.java

/**
 * @author Vaclav Bohac 
 * This program shows size of memory allocated by
 * JVM for primitive types.
 */

import java.lang.reflect.Field;


public class sizes {
	
	/**
	 * Size of the single byte in bits.
	 */
	public static final int BYTESIZE = 8;



	/**
	 * Returns the size in bytes.
	 * @param  int size of the type in bits
	 * @return int
	 */
	public static int byteSize(int size)
	{
		return size / BYTESIZE;
	}



	/**
	 * Makes print statement much shorter.
	 * @param  string s string to print
	 * @param  boolean[] print to error output
	 * @return void
	 */
	public static void print(String s, boolean... error)
	{
		if (error.length > 0 && error[0] == true) {
			System.err.println(s);
			return;
		}
		System.out.println(s);
	}



	public static void main(String[] args)
	{

		print("Sizes of primitive types in bytes:");

		String[] names = {
			"java.lang.Integer",
			"java.lang.Long",
			"java.lang.Short",
			"java.lang.Float",
			"java.lang.Double",
			"java.lang.Character"
		};

		try {

			for (int i = 0, length = names.length, size = 0; i < length; i += 1) {
				Class c = Class.forName(names[i]);
				Field f = c.getField("SIZE");
				size = byteSize(f.getInt(f)); 
				print(names[i] + ": " + Integer.toString(size));
			}

		} catch (Exception e) {
			print(e.getMessage(), true);
		} 

	}
}