Generic Array Creation Error

Question:

When attempting to create an array of generic classes using an expression like:

public static ArrayList[] a = new ArrayList[2];

Java reports a "Generic array creation" error. Why is this not allowed?

Answer:

Java arrays do not support generics. Specifically, the Java Virtual Machine (JVM) verifies bytecode to ensure that generic array types are not declared. This is because allowing generic arrays would introduce the potential for runtime conversion errors, known as the "erasure problem."

Alternative Solutions:

1. Use a Collection Instead:

   • Consider using a standard collection class like ArrayList> instead of an array.

2. Create an Auxiliary Class:

   • Define a new class, such as MyObjectArrayList that extends ArrayList. Arrays of MyObjectArrayList can then be created.

3. Avoid Unchecked Conversions:

   • Avoid attempts to convert generic arrays to non-generic arrays, as this can lead to type safety issues.