Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
576 views
in Technique[技术] by (71.8m points)

java - Iterate to find a Map entry at an index?

I have a LinkedHashMap. I want to get the Foo at index N. Is there a better way of doing this besides iterating until I find it?:

int target = N;
int index = 0;
for (Map.Entry<String, Foo> it : foos.entrySet()) {
    if (index == target) {
        return it.getValue();
    }
    index++;
}

I have to do get random elements from the map by an index about 50 times for some operation. The map will have about 20 items in it.

Thanks

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)
List<Entry<String,Foo>> randAccess = new ArrayList<Entry<String,Foo>>(foos.entrySet());

Then for index N with O(1) access...

randAccess.get(N)

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...