Best practice for getting datatype size(sizeof) in Java

Question

I want store a list of doubles and ints to a ByteBuffer, which asks for a size to allocate. I\'d like to write something like C\'s syntax

int size=numDouble*size         


        

Answer 1

Write your own method. In Java the datatypes are platform independent always the same size:

public static int sizeof(Class dataType)
{
    if (dataType == null) throw new NullPointerException();

    if (dataType == int.class    || dataType == Integer.class)   return 4;
    if (dataType == short.class  || dataType == Short.class)     return 2;
    if (dataType == byte.class   || dataType == Byte.class)      return 1;
    if (dataType == char.class   || dataType == Character.class) return 2;
    if (dataType == long.class   || dataType == Long.class)      return 8;
    if (dataType == float.class  || dataType == Float.class)     return 4;
    if (dataType == double.class || dataType == Double.class)    return 8;

    return 4; // 32-bit memory pointer... 
              // (I'm not sure how this works on a 64-bit OS)
}

Usage:

int size = numDouble * sizeof(double.class) + numInt * sizeof(int.class);