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Write once, run everywhere! Ale jen ocuť pocuť.

Dneska jsem zkoumal, proč nám některé testy pracují správně s Oracle Javou (1.6), ale pod IBM Javičkou padají. A výsledek mého bádání mě ohromil. Člověk by doufal, že alespoň třídy v balíku java.lang budou implementovány obdobně. A prdlajz!

Náš problém má původ v rozdílné implementaci metody Class.getMethods(), která toho občas u IBM vrátí o něco více než u Oraclu. Nejsem si zatím jistý, která implementace odpovídá JLS lépe, ale do dneška jsem předpokládal, že kvůli takovýmto problémům existuje TCK.

Chcete-li si problém vyzkoušet sami, zde je kód:

/**
 * This class is a reproducer for different results returned from Oracle and IBM Class.getMethod() call.
 * 
 * @author Josef Cacek
 */
public class GetMethodsProblemReproducer {

    // Public methods --------------------------------------------------------

    /**
     * Main method.
     */
    public static void main(String[] args) {
        System.out.println("Java: " + System.getProperty("java.version") + " " + System.getProperty("java.vendor"));
        System.out.println("Length of array returned by B.class.getMethods() call: " + B.class.getMethods().length);
    }

    // Embedded classes ------------------------------------------------------

    public static class A {
        public static void test() {
        }
    }

    public static class B extends A {
        public static void test() {
        }
    }
}

Výsledek pro Oracle Javu:

Java: 1.6.0_31 Sun Microsystems Inc.
Length of array returned by B.class.getMethods() call: 10

Výsledek pro IBM Javu:

Java: 1.6.0 IBM Corporation
Length of array returned by B.class.getMethods() call: 11

Jak jste jistě již sami správně vydedukovali, problém se vyskytne v případě, že "překrýváme" (nebo správněji skrýváme) veřejnou statickou metodu předka.

Komentáře

Anonymní píše…
Tak tohle je pro mne zatim spanelska vesnice :)
daniel.svoboda@areazkh.cz píše…
Dobry den vazeny pane Cacek, presto, ze jiz dale neupravujete Jsignpdf, velmi prosím o kontakt na vás kvůli dotazu k tomuto programu.
S diky a pozdravem Daniel Svoboda. daniel.svoboda@areazkh.cz

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