I know that generic arrays are not supported by Java, but I don't know how to fix this so it will work

Question

I'm try to create a HashTable and this part of the code requires an array, but when it's not delcared generic I get unchecked warnings, but I know that generic arrays aren't supported, but I'm not sure how to fix this.

array = new HashEntry<AnyType>[ nextPrime( arraySize ) ];

`@SuppressWarnings("unchecked")` is the canonical approach here. — Marko Topolnik, Dec 01 '14 at 22:03
You may find http://stackoverflow.com/questions/12366035/why-does-java-arraylist-use-per-element-casting-instead-of-per-array-casting helpful — meriton, Dec 01 '14 at 22:14
@MarkoTopolnik Thorough tests are always good, but they won't prove a negative (lack of heap pollution). — chrylis -cautiouslyoptimistic-, Dec 01 '14 at 23:30
@chrylis You can write tests which make every effort to cause heap pollution, and the test can definitely know when it has happened. — Marko Topolnik, Dec 02 '14 at 08:39

score 1 · Answer 1 · answered Dec 01 '14 at 22:19

I suggest checking out JDK's own code for HashMap, specifically the resize method and these lines:

    @SuppressWarnings({"rawtypes","unchecked"})
        Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];

newTab is then assigned to the main instance variable, table. So, if JDK can't avoid @SuppressWarnings, neither will you.

MJSG · Answer 2 · 2014-12-02T04:59:06.680

0

Write it as such

@SuppressWarnings("unchecked")
HashEntry<K, V>[] array = new HashEntry[nextPrime()];

then add @SuppressWarnings("unchecked") to it.

edited Dec 02 '14 at 04:59

answered Dec 01 '14 at 22:07

MJSG

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When I do that, I get an identifier expected error @MJSG – Dec 02 '14 at 02:33

score 0 · Answer 3 · answered Dec 01 '14 at 23:01

Don't use arrays. Use collections.

Using arrays requires more code, more care and gives no measurable benefit.

Using collections leverages the code and care built into the JDK.
If you've got an array of HashEntry, you're most of the way to a Map - just use a constant order map:

Map<SomeKey, SomeValue> map = new LinkedHashMap<SomeKey, SomeValue>();

I know that generic arrays are not supported by Java, but I don't know how to fix this so it will work

3 Answers3