Java Instantiate new Map.Entry-array

Question

I'm having problems casting an object array to a key-value pair array, with generic types for the key and value objects. Here is a minimal example.

public class Main {
    public static void main(String[] args) {
        array = (Map.Entry<Integer, Integer>[]) new Object[1];
    }

    private static Map.Entry<Integer, Integer>[] array;
}

Changing Map.Entry to a class (rather than interface) doesn't do the trick either.

Error trace:

run:
Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.util.Map$Entry;
        at lab2.Main.main(Main.java:13)
Java Result: 1

Solution

Do you need to have an array? You can do the following with a List:

public static void main(String[] args) {
    array = new ArrayList<Map.Entry<Integer, Integer>>();
}

private static List<Map.Entry<Integer, Integer>> array;

Alternately, you can instantiate the non generic type, and cast to the generic type:

public static void main(String[] args) {
    array = (Map.Entry<Integer, Integer>[])new Map.Entry[1];
}

private static Map.Entry<Integer, Integer>[] array;

However, this will give you warnings, and is generally not preferred.