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I have been trying to create my own library to serialize and de-serialize primitive types from a class to xml and from xml to a class instance using reflection to examine method naming patterns and method return types.

So far I have been able to do this with all the basic primitive types but I got stuck on serializing an array of the same primitives.

For example I invoke the class method to get the array of primitives:

method.invoke(clazz, (Object[])null);

This method will return only a primitive array int[], double[], float[], char[] etc. though we don't know which one it will be.

I have tried using a generic such as

T t = (T)method.invoke(clazz, (Object[])null);
T[] t = (T[])method.invoke(clazz, (Object[])null);

But it doesn't let me cast from the primitive array to an object.

And you can't use Array.newInstance assuming we don't know the type.

Is there a way that I can convert this array of primitives to say an Object array in a generic manner.

In a generic manner meaning without needing to know or checking what the type of the array is. Or should I just cycle through all the primitive types and handle all of them separately.

I can do this both ways the only reason I want to do this in a generic manner is to cut down on the redundant code.

Thanks in advance.

share|improve this question
    
+1 Great question! –  Paul Bellora Jun 1 '13 at 4:30

3 Answers 3

up vote 9 down vote accepted

You can use the Array utility class

public static Object[] toObjectArray(Object array) {
    int length = Array.getLength(array);
    Object[] ret = new Object[length];
    for(int i = 0; i < length; i++)
        ret[i] = Array.get(array, i);
    return ret;
}
share|improve this answer
1  
It worked perfectly. I never thought that I could access the object as an array. Thank you. –  Andrew Cumming May 31 '13 at 21:39
up vote 0 down vote

Does java.lang.reflect.Array.get() do what you want?

share|improve this answer
    
You also need the getLength() –  Peter Lawrey May 31 '13 at 21:32
    
It would be my next step. This would allow me to get an item from the array but I still need to know how to store it in a proper array first. –  Andrew Cumming May 31 '13 at 21:32
up vote 0 down vote 
Object result = method.invoke(clazz, (Object[])null);
Class<?> arrayKlazz = result.getClass();
if (arrayKlazz.isArray()) {
    Class<?> klazz = result.getComponentType();
    if (klazz == int.class) {
        int[] intArray = arrayKlazz.cast(result);
    }
}

It seems more appropiate to hold (primitive) arrays in an Object (result above).

share|improve this answer
    
How will this help get an Object[] from the result? –  Peter Lawrey May 31 '13 at 21:34
    
Object[] is already answered. But solving the problem of serialization with Object[] for an int[], double[] etcetera seems a bit going too far. A general array should be held in an Object. I want to suggest that without too large emphasis. If an Object[] is wished - fine. –  Joop Eggen May 31 '13 at 21:40

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