How to Ensure Immutability for Primitive Arrays in Java?

Immutable Arrays in Java

The primitive array type in Java does not offer immutability. Declaring an array as final merely protects the reference to the array from being reassigned, but does not prevent modifications to individual array elements.

To enforce immutability for an array of primitives, you must consider using an alternative data structure.

Unmodifiable List as an Alternative

An immutable alternative to primitive arrays is using the Collections.unmodifiableList() method to create an unmodifiable list backed by the array elements. This method returns a wrapper list that prevents any modifications to its contents.

<code class="java">List<Integer> items = Collections.unmodifiableList(Arrays.asList(0, 1, 2, 3));</code>

Once the unmodifiable list is created, any attempt to modify its elements will result in an UnsupportedOperationException. This ensures that the elements of the array remain unchanged while still allowing access to their values through the list interface.

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