Java: want binary search of subset of an array

Question

In Java, Arrays.binarySearch always searches the entire array. Sometimes part of the array has not been filled. Is there any function to search a part of the array, e.g.

int binarySearch(int[] a, int end, int value)

Yes, I could just use a TreeMap<Integer> but I have a lot of these and TreeMap<Integer> uses several times more memory than int[].

And yes, I can certainly write a binary search, but given the presence of Arrays.binarySearch it seems I shouldn't have to write my own.

NPE · Accepted Answer · 2012-06-13 19:35:39Z

10

There is an overloaded Arrays.binarySearch() that does exactly this:

public static int binarySearch(int[] a,
                               int fromIndex,
                               int toIndex,
                               int key)

It is available in Java 1.6+.

answered Jun 13, 2012 at 19:35

NPE

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2 Comments

kevin cline Over a year ago

Oh duuuuuh! For some reason Google 'Java X' always presents old doc first. Now I feel silly for asking. If I could downvote my own question, I would.

NPE Over a year ago

@kevincline: You are quite right about Google and old Java docs. I usually search for java6 or java7, e.g. Arrays java6.

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