How to Resolve ClassCastException: Arrays.asList Cannot Be Cast to ArrayList in Java?

Why am I encountering a ClassCastException when casting Arrays.asList to ArrayList in Java?

List<String> list = Arrays.asList("One", "Two", "Three");
ArrayList<String> arrayList = (ArrayList<String>) list; // This line causes ClassCastException

The error occurs because the list returned by Arrays.asList() is an instance of a private static class that does not inherit from ArrayList. This results in a ClassCastException when casting to ArrayList directly.

List<String> originalList = Arrays.asList("Apple", "Banana", "Cherry");
ArrayList<String> arrayList = new ArrayList<>(originalList); // Correct way to create ArrayList from Arrays.asList()

Causes

• You are trying to cast the result of Arrays.asList() directly to ArrayList, which is incorrect because it's an instance of a different class (java.util.Arrays$ArrayList).
• Arrays.asList returns a fixed-size list backed by the specified array, not an ArrayList. Attempting to cast it will lead to ClassCastException.

Solutions

• To avoid this error, instead of casting, create a new ArrayList using the list returned from Arrays.asList(): List<String> list = Arrays.asList("One", "Two", "Three"); ArrayList<String> arrayList = new ArrayList<>(list);
• This way, you are creating a new ArrayList that contains the elements of the list.

Mistake: Directly casting the result of Arrays.asList to ArrayList.

Solution: Always use 'new ArrayList<>(list)' to create an ArrayList from the returned list.

Mistake: Assuming that the list returned by Arrays.asList is modifiable.

Solution: Understand that the list returned by Arrays.asList is fixed size and cannot be changed.