"handle or declare" requirement, 360, 362
HAS-A relationships, 92–94, 153
hashCode(), 529–536
contract in Java does, 534–536
examples of use by collections, 530–532
implementing, 532–534
Object class, 529–536
overriding, 529–530
public methods, 528
two-minute drill, 606–607
HashMap, 543, 563–564
HashSet, 542
Hashtable, 544
hasNext(), 560
heap, 174–175, 255
hexadecimal literals, 178
high cohesion, in OO design, 148