Java 16: Record compact constructor for validation

A compact constructor validates or normalizes fields before assignment.

Code

record Range(int lo, int hi) {
    Range {
        if (lo > hi) throw new IllegalArgumentException("lo > hi");
    }
}
System.out.println(new Range(1, 10));
try { new Range(5, 2); } catch (IllegalArgumentException e) {
    System.out.println("rejected: " + e.getMessage());
}

Output

Range[lo=1, hi=10]
rejected: lo > hi

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Published 2026-07-26