Java ArrayList 搜索 [英] Java ArrayList search

问题描述

我有一个 String 类型的 ArrayList.我想确定这个 ArrayList 的任何元素是否以指定的字符串开头，如果 ArrayList 包含这个元素，那么我想获取这个元素的索引.另外，我不想循环这个 ArrayList 来获取那个元素的索引.

I have an ArrayList of type String. I want to determine whether any element of this ArrayList starts with a specified string and if the ArrayList contains this element, then I want to get the index of this element. In addition, I do not want to loop this ArrayList to get the index of that element.

例如:

ArrayList<String> asd = new ArrayList<String>();  // We have an array list

//We filled the array list
asd.add("abcc trtiou");
asd.add("aiwr hiut qwe");
asd.add("vkl: gtr");
asd.add("aAgiur gfjhg ewru");

现在，我想通过使用 vkl: 而不循环数组列表来获取元素 vkl: gtr 的索引.(搜索也应该不区分大小写，所以，使用 vkl: 和 VkL: 应该给出 vkl: gtr)

Now, I want to get the index of the element vkl: gtr by using vkl: without looping array list.(searching also should be case insensitive, so, using vkl: and VkL: should give the index of vkl: gtr)

我该怎么做?

提前致谢.

推荐答案

你必须循环 ArrayList.您不可能只访问一个索引并保证它就是您要查找的索引.

You have to loop the ArrayList. You cant possibly access just a single index and be guaranteed it is what you're looking for.

此外，如果涉及大量搜索，您应该考虑使用其他数据结构.搜索一个 ArrayList 需要 O(n) 时间，而像红黑树这样的事情可以在 O(log n) 中完成.

Also, you should consider using another data structure if a lot of searching is involved. Searching an ArrayList takes O(n)time while something like a red-black tree can be done in O(log n).

如果您在程序执行之前知道用于定位结构中项目的字符串，请考虑使用 HashMap.您可以访问 O(1) 中的项目.

If you know before program execution the strings used to locate the items in the structure, consider using a HashMap. You can access the items in O(1).

如果这些解决方案中没有一个适合您的特定问题，那么我们可以通过您尝试执行的操作来扩展您的答案，我们可以提供更好的答案，说明您如何以最少的搜索时间找到您的项目.

If none of these solutions suit your particular problem expand on your answer with what you're trying to do, we could provide a better answer as to how you'd locate your items with minimal search time.

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