如何从Java中的java.lang类型的对象获取对等原始类型？

Question

Now is there an easy way to do so? Let's say that I have an Object that could be Long, Float, Integer, Byte, etc, how do I get its equivalelent primitive class (Class) from this object?

A method could be written like this

Class<?> getEquivalentPrimitiveType(Object obj)
{
}

Answer 1

The corresponding primitive type is Long.TYPE :

public static final Class<Long> TYPE

The Class instance representing the primitive type long .

If you have an instance of a "wrapper" class, you can get the corresponding primitive through reflection, like this:

static <T> Class<T> getPrimitive(Class<T> wrapper)
    throws NoSuchFieldException, IllegalAccessException {
    return (Class<T>)wrapper.getDeclaredField("TYPE").get(null);
}

Here is a demo on ideone .