FULL PRODUCT VERSION :


A DESCRIPTION OF THE PROBLEM :
In the implementation of java.util.EnumMap.equals, when testing against another EnumMap, it iterates and compares the contents of both maps, but this iteration could/should be skipped whenever the maps are a different size.

Current code:

    private boolean equals(EnumMap<?,?> em) {
        if (em.keyType != keyType)
            return size == 0 && em.size == 0;
        
        // Key types match, compare each value
        for (int i = 0; i < keyUniverse.length; i++) {
            Object ourValue = vals[i];
            Object hisValue = em.vals[i];
            if (hisValue != ourValue &&
                (hisValue == null || !hisValue.equals(ourValue)))
                return false;
        }
        return true;
    }

Proposed change:

    private boolean equals(EnumMap<?,?> em) {
        if (size != em.size)
            return false;
        
        if (keyType != em.keyType)
            return size == 0;
        
        // Sizes and key types match, compare each value
        for (int i = 0; i < keyUniverse.length; i++) {
            Object ourValue = vals[i];
            Object hisValue = em.vals[i];
            if (hisValue != ourValue &&
                (hisValue == null || !hisValue.equals(ourValue)))
                return false;
        }
        
        return true;
    }


REPRODUCIBILITY :
This bug can be reproduced always.