在内存和计算方面,哪一种是更有效的访问(关键,价值)对子的方法:读取属性文件,使用属性“getProperty”(“键”)读取,或者将整个属性文件装入程序开始时的哈什马普,然后在哈什马普查找密钥?
此外,如果从属性中得出的值中只有1个被反复使用,是否最好在成员变量中存储该值并访问该变量,或者每次使用属性时都查找该值。 getProperty (“密钥 ”)?
property.get Property (“键”) 是来自 Hashable 的查询, 即属性对象。 当您进行 property.load () 时, 从文件装入条目, 并将其存储到扩展 Hashable 的属性对象中。 对属性的每一次访问都会在 Hashable 中查找。 没有 IO 文件了 。
当然,访问成员变量比从Hashmap 的钥匙中获取一个值要快一点,但我怀疑这是您在性能方面能取得任何显著成果的地方。一个Hashmap 的查看是 O(1), 速度非常快 。 您可能需要数百万次的查看才能发现差异。 做最容易读的东西 。
实际上, System.getProperty () 使用一个 java. util. property 对象内部。 property 类扩展了 HashTable<Object,Object> , 所以 so so so so so 将使用 HashMap 来明确表达, 不太可能获得很多的性能。
然而, 如果您经常使用少量属性, 如果将这些属性存储在变量中, 肯定会有帮助 。 Hashtable/ HashMap 查看和可变访问可能都是 O(1), 但是 Hashtable 查看肯定有一个更大的常数系数 。
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