How to create a safe generic array object in java?

Question

Hey this is my first post and i have this problem as you can see this the required method enter image description here

so i tried to create an array but an exception is showed so is there any suggestions ?

this my code

public class GArrayFactory {

// Create and return an array of size n

public static <T extends Comparable<T>> GArray<T>[] getGArray(int n) {

    GArray<T>[] array = (GArray<T>[]) new Object[n];

    return array ;

and this the exception

Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [LGArray;
at GArrayFactory.getGArray(GArrayFactory.java:9)

Looks like you've made a typo in your code. Notice `LGarray` instead of `GArray`. — RaminS, Feb 03 '19 at 15:17
@Gendarme No, that is just how reference descriptors are composed, i.e. `"L" + + ";"`. — Jorn Vernee, Feb 03 '19 at 15:22
the screenshot you attached has `GArray` return type, but not `GArray[]` as in the code. Which one is required ? — Ruslan, Feb 03 '19 at 15:48
This is also a good duplicate: https://stackoverflow.com/questions/529085/how-to-create-a-generic-array-in-java — RaminS, Feb 03 '19 at 15:55
@Gendarme The component type of the array they're trying to create isn't a type coming from a type parameter.. — Sotirios Delimanolis, Feb 03 '19 at 16:03

score -1 · Answer 1 · answered Feb 03 '19 at 15:31

You can create generic arrays using this method:

public class GArrayFactory<E> {

    private E[] array;

    public GArrayFactory(Class<E> clazz, int size) {
        final E[] array = (E[]) Array.newInstance(clazz, size);
        this.array = array;
    }

    public E[] getArray() {
        return array;
    }
}

Further explanation can be found here

How to create a safe generic array object in java?

1 Answers1