MemorySizes.java

package com.joe.utilities.core.util;

/**
 * Holds sizes of Java primitives
 * This is used with MemoryCounter class to estimate heap size of objects using reflections
 * @link http://www.javaspecialists.co.za/archive/Issue078.html
 */
import java.util.IdentityHashMap;
import java.util.Map;

public class MemorySizes
{
	private final Map<Object, Integer> primitiveSizes = new IdentityHashMap<Object, Integer>()
	{
		{
			put(boolean.class, new Integer(1));
			put(byte.class, new Integer(1));
			put(char.class, new Integer(2));
			put(short.class, new Integer(2));
			put(int.class, new Integer(4));
			put(float.class, new Integer(4));
			put(double.class, new Integer(8));
			put(long.class, new Integer(8));
		}
	};

	public int getPrimitiveFieldSize(Class clazz)
	{
		return ((Integer) primitiveSizes.get(clazz)).intValue();
	}

	public int getPrimitiveArrayElementSize(Class clazz)
	{
		return getPrimitiveFieldSize(clazz);
	}

	public int getPointerSize()
	{
		return 4;
	}

	public int getClassSize()
	{
		return 8;
	}
}