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有啥区别

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求女票上微博

#1 Created at ... [Delete] [Delete and Lock User]

public class aaa {

public static void main(String[] args) {
Map<DayOfWeek, String> map = new EnumMap<>(DayOfWeek.class);
map.put(DayOfWeek.MONDAY, "星期一");
map.put(DayOfWeek.TUESDAY, "星期二");
map.put(DayOfWeek.WEDNESDAY, "星期三");
map.put(DayOfWeek.THURSDAY, "星期四");
map.put(DayOfWeek.FRIDAY, "星期五");
map.put(DayOfWeek.SATURDAY, "星期六");
map.put(DayOfWeek.SUNDAY, "星期日");
System.out.println(map);
System.out.println(map.get(DayOfWeek.MONDAY));

Map<DayOfWeek, String> map1 = new HashMap<>();
map1.put(DayOfWeek.MONDAY, "星期一");
map1.put(DayOfWeek.TUESDAY, "星期二");
map1.put(DayOfWeek.WEDNESDAY, "星期三");
map1.put(DayOfWeek.THURSDAY, "星期四");
map1.put(DayOfWeek.FRIDAY, "星期五");
map1.put(DayOfWeek.SATURDAY, "星期六");
map1.put(DayOfWeek.SUNDAY, "星期日");
System.out.println(map1);
System.out.println(map1.get(DayOfWeek.MONDAY));

}

}

Joker.fu_95

#2 Created at ... [Delete] [Delete and Lock User]

如果作为key的对象是enum类型，内部以一个非常紧凑的数组存储value，并且根据enum类型的key直接定位到内部数组的索引，并不需要计算hashCode()，不但效率最高，而且没有额外的空间浪费

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