How to create an array with Generic type?

Question

Hi,
I need to create a typed array T[] from an object array Object[]. This is due to legacy code integration with older collections.
The method signature is simple:public static <T> T[] toTypedArray(Object[] objects)I tried using multiple implementations and go over them in the debugger. None of them create a typed collection as far as I can tell. The type is always Object[].
A simple implementation is just to cast the array and return, however this is not so safe.
What is interesting is that if I create ArrayList<String>, the debugger shows the type of the array in the list as String[].
If I create ArrayList<T>, the class contains Object[] and not T[].
I also triedT[] array = (T[]) Array.newInstance(T[].class.getComponentType(), objects.length);And a few other combinations. All work at runtime, create multiple compilation warnings, and none actually creates T[] array at runtime.
Maybe I am missing something, but Array.newInstace(...) is supposed to create a typed array, and I cannot see any clean way to pass Class<T> into it.T[].class.getComponentType()Returns something based on object and not on T, and T.class is not possible.
So is there anything really wrong here, or should I simply cast the array and live with the warnings?
Any help appreciated!

Answer 1

Ok. May be you could keep information about generic type in the your class:
public class Util {
    public static <T> T[] toTypedArray(Class<T> cls, Object[] objects){
        int size = objects.length;
        T[] t = (T[]) java.lang.reflect.Array.newInstance(cls, size);
        System.arraycopy(objects, 0, t, 0, size);
        return t;
public class Sample<T> {
    Class<T> cls;
    T[] array;
    public Sample(Class<T> cls) {
        this.cls = cls;
    public void setArray(Object[] objects){
        array = Util.toTypedArray(cls, objects);
    public T[] getArray(){
        return array;
    public static void main(String[] args) {
        Object[] objects = new Object[] { new LinkedList(), new ArrayList()};
        Sample<List> myClass = new  Sample<List>(List.class);
        myClass.setArray(objects);
        for(List elem: myClass.getArray()){
            System.out.println(elem.getClass().getName());
}