Java™ How To Program (Early Objects), Tenth Edition

16.7.4 Method binarySearch

The high-speed binary search algorithm—which we discuss in detail in Section 19.4—is built into the Java collections framework as a static Collections method binarySearch. This method locates an object in a List (e.g., a LinkedList or an ArrayList). If the object is found, its index is returned. If the object is not found, binarySearch returns a negative value. Method binarySearch determines this negative value by first calculating the insertion point and making its sign negative. Then, binarySearch subtracts 1 from the insertion point to obtain the return value, which guarantees that method binarySearch returns positive numbers (>= 0) if and only if the object is found. If multiple elements in the list match the ...