Binary search is a popular search algorithm that is used to search for a specific element in a sorted array or list. The algorithm works by repeatedly dividing the search interval in half until the target value is found or the search interval is empty.

In Java, the binary search algorithm is implemented as a method in the Arrays class, which is part of the java.util package. The signature of the method is as follows: 

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

The method takes two arguments: the sorted array a and the key value to be searched key. It returns the index of the element if found, or a negative value if the element is not present in the array.

The binary search algorithm is efficient because it has a time complexity of O(log n) in the worst case, where n is the number of elements in the array. This makes it suitable for searching large arrays quickly.

However, it is important to note that the binary search algorithm only works on sorted arrays, so if the array is not sorted, it must be sorted first before the algorithm can be applied. Additionally, the algorithm assumes that the elements in the array are unique, so duplicates must be handled appropriately.