[問題] OCJP SE6題目 - enum
Given:
enum Example {ONE, TWO, THREE}
Which statement is true?
A. The expressions (ONE == ONE) and ONE.equals(ONE) are both guaranteed to be
true.
B. The expression (ONE < TWO) is guaranteed to be true and ONE.compareTo(TWO)
is guaranteed to be less than one.
C. The Example values cannot be used in a raw java.util.HashMap; instead, the
programmer must use a java.util.EnumMap.
d. The Example values can be used in a java.util.SortedSet, but the set will
NOT be sorted because enumerated types do NOT implement java.lang.Comparable
------------------
The answer: A
想請問B,C,D是哪部分錯了, 這題不會得太多,實在沒有辦法做判斷。
A我倒是較能理解,因為ONE其實會是一個繼承Enum的類別,所以ONE==ONE物件記憶體位置
相同; ONE.equals(ONE), 我只知道System.out.println(Example.ONE); 會得到字串
ONE, 所以知道會對。
跟大家請教一下了,謝謝
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修正錯字 java."util".SortedSet
※ 編輯: uopsdod (180.217.174.122), 02/20/2017 21:03:35
修正錯字 java.util.HashMap
※ 編輯: uopsdod (180.217.174.122), 02/20/2017 21:04:41
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修正錯字 enum Example
※ 編輯: uopsdod (180.217.174.122), 02/20/2017 21:06:27
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