Check type of primitive field

Question

I'm trying to determine the type of a field on an object. I don't know the type of the object when it is passed to me but I need to find fields which are 'long's. It is easy enough for Longs but the primitive long seems more difficult.

I can make sure that the objects passed to me only have Longs not the primitives but I'd rather not. So what I have is:

for (Field f : o.getClass().getDeclaredFields()) {
    Class<?> clazz = f.getType();
    if (clazz.equals(Long.class)) {
        // found one -- I don't get here for primitive longs
    }
}

A hacky way, which seems to work, is this:

for (Field f : o.getClass().getDeclaredFields()) {
    Class<?> clazz = f.getType();
    if (clazz.equals(Long.class) ||  clazz.getName().equals("long")) {
        // found one
    }
}

I'd really like a cleaner way to do this if there is one. If there is no better way then I think that requiring the objects I receive to only use Long (not long) would be a better object.

Any ideas?

Answer 1

Your using the wrong constant to check for Long primitives - use Long.TYPE, each other primitive type can be found with a like named constnat on the wrapper. Byte.TYPE, Character.TYPE etc.

Answer 2

o.getClass().getField("fieldName").getType().isPrimitive();

Answer 3

You can just use

byte.class
char.class
short.class
float.class
long.class
double.class
void.class

If you are using reflection, why do you care, why do this check at all. The get/set methods always use objects so you don't need to know if the field is a primitive type (unless you try to set a primitive type to the null value.)

In fact, for the method get() you don't need to know which type it is. You can do

// any number type is fine.
Number n = field.get(object);
long l = n.longValue();