How to Create an Array of LinkedLists in Java: Overcoming Type Erasure?

Array of LinkedLists in Java: Creation and Pitfalls

When attempting to create an array of LinkedLists in Java, developers may encounter an error stating that a generic array of LinkedList is not permitted. This issue arises because of the language's type erasure, and the solution involves casting the array type during creation.

In the provided code, the declaration of the array myMatrix as private LinkedList[] is valid, as Java allows generic types in declarations. However, during instantiation, the compiler realizes that it cannot create an array of concrete classes (here LinkedList).

To resolve this issue, the code must cast the array type to a generic type during creation. The correct syntax is:

<code class="java">myMatrix = (LinkedList<IntegerNode>[]) new LinkedList<?>[numRows];</code>

By casting to a generic type (in this case, LinkedList), the compiler is informed that the array can hold any type of LinkedList. This allows the instantiation to complete successfully.

It's worth noting that type erasure in Java means that the specific type of objects stored in the array is lost at runtime. This means that the array can hold different types of LinkedLists, but it will not have type information to distinguish between them.

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