多项选择题
A.The class implements java.lang.Comparable.
B.The class implements java.util.Comparator.
C.The interface used to implement sorting allows this class to define only one sort sequence.
D.The interface used to implement sorting allows this class to define many different sort sequences.
单项选择题 A programmer has an algorithm that requires a java.util.List that provides an efficient implementation of add（0， object）， but does NOT need to support quick random access. What supports these requirements？（）
多项选择题 Given： Which two code fragments， inserted independently at line 5， will compile without warnings？（）
多项选择题 Given： A programmer is developing a class Key， that will be used as a key in a standard java.util.HashMap. Which two methods should be overridden to assure that Key works correctly as a key？（）