RFR: 8371501: Change IAE to NPE in java.awt.image.Kernel when data is null

[Alexey Ivanov]

On Wed, 12 Nov 2025 02:54:08 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

> This is an update to the patch integrated in https://github.com/openjdk/jdk/pull/28127. It changes the exception from IllegalArgumentException back to NullPointerException, which was thrown previously.
> 
> Rationale:
>  - Since an NPE was already thrown before, this does not introduce a behavior change
>  - Throwing NPE on null is the common pattern used across the codebase, including in the affected package
> 
> Additional notes:
> The patch uses the idiomatic way to check parameters for null via Objects.requireNonNull(). I am not sure whether this code path is performance critical. The use of >> 1 instead of / 2 suggests that performance might matter. If this code is performance sensitive, we can remove the Objects.requireNonNull() call, because even without it the resulting NPE would still clearly show which variable was null when its field was accessed.
> 
> It is also possible to remove the use of multiplyExact(). We can simply multiply width/height as long values and compare the result with the data length. In case of overflow, the existing “Data array too small” exception would still be thrown.

Looks good except for a minor comment in the test.

test/jdk/java/awt/image/ConvolveOp/KernelInitialisationTest.java line 49:

> 47:             System.err.println("Expected: " + expected);
> 48:             System.err.println("Actual: " + actual);
> 49:             throw new RuntimeException("Test failed");

Does it make sense to include the class names in the error message too? It helps analysing the failure, you know the reason without opening the log file.

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Marked as reviewed by aivanov (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/28249#pullrequestreview-3504115865
PR Review Comment: https://git.openjdk.org/jdk/pull/28249#discussion_r2559237017