Decimal64Utils.equals(long,Object) implementation contains a pitfall

[andymalakov]

User tried to use this method with

Map<String,Long> prices = ... 

long price = Decimal64Util.parse("229");
prices.put("AAPL", price);

boolean samePrice =  (Decimal64Util.equals(price, prices.get("AAPL")); // returns FALSE (where TRUE is expected)

At minimum we should update javadoc. But I would rather support Long (boxed version of long).

Alternatively: Any specific reason the method signature takes java.lang.Object instead of Decimal64 as second argument.

    /**
     * Returns {@code true} if two {@code DFP} values represent the same arithmetical value.
     * <p>
     * We consider that all possible encodings of {@link #POSITIVE_INFINITY} are equal,
     * all possible encodings of {@link #NEGATIVE_INFINITY} are equal,
     * all possible encodings of NaN and SNaN are equal,
     * all invalid encodings of finite values equal {@link #ZERO}
     *
     * @param a the first 64-bit DFP value.
     * @param b the second 64-bit DFP value.
     * @return {@code true} if two decimal values represent the same arithmetical value.
     */
    public static boolean equals(@Decimal final long a, final Object b) {
        return (b == null && NULL == a)
            || (b instanceof Decimal64 && equals(a, ((Decimal64) b).value));
    }

[alexei-osipov]

Please note that the provided code is not really a good example of DFP API use. If you want to use boxed type instead of a primitive long and have correct behavior, you should use Decimal64 class, not a Long:

Map<String, Decimal64> cache = new HashMap<>(); // Decimal64 instead of Long!
Decimal64 val = Decimal64.fromDouble(0.5); // Boxed value, instead of a primitive long
cache.put("val", val);
@Decimal long val2 = Decimal64Utils.fromDouble(0.5);

// Compare unboxed value with boxed value (the best way for this case)
assertTrue(Decimal64Utils.equals(val2, cache.get("val")));

// Compare boxed values
Decimal64 value2boxed = Decimal64.fromUnderlying(val2);
assertTrue(value2boxed.equals(cache.get("val")));
assertTrue(value2boxed.compareTo(cache.get("val")) == 0);

// Compare binary representations
assertTrue(val2 == Decimal64.toUnderlying(cache.get("val")));
assertTrue(Decimal64Utils.compareTo(val2, Decimal64.toUnderlying(cache.get("val"))) == 0);