Binary search is an optimized solution for searching an element in an array as it reduces search time by following three ways Either the element to be searched can be the middle element.
All useful information for classes jdk usage is very often is the documentation : "Searches the specified list for the specified object using the binary search algorithm. The list must be sorted into ascending order according to the natural ordering of its elements (as by the sort (List) method) prior to making this call.
That's n/2 or linear time. With a binary search, you eliminate 1/2 the possible entries each iteration, such that at most it would only take 7 compares to find your value (log base 2 of 128 is 7 or 2 to the 7 power is 128.) This is the power of binary search.
A linear search looks down a list, one item at a time, without jumping. In complexity terms this is an O(n) search - the time taken to search the list gets bigger at the same rate as the list does. A binary search is when you start with the middle of a sorted list, and see whether that's greater than or less than the value you're looking for, which determines whether the value is in the first ...
well this binary search is used by two other methods : find and insert. insert calls binarysearch and the index is always either the index of a duplicate or address where the string should be inserted to keep list sorted. for find you simply check if buf [index] == string we are looking for .