To implement a binary search in Java, you can follow these steps:

1. Ensure that the array is sorted in ascending order. Binary search requires a sorted array to work correctly.
2. Define a method that takes the sorted array, the target element to search for, and the indices of the subarray to search within.
3. Calculate the middle index of the subarray by taking the average of the start and end indices: int mid = (start + end) / 2.
4. Compare the target element with the element at the middle index:
   • If they are equal, return the middle index as the position of the target element.
   • If the target element is less than the middle element, recursively call the binary search method on the left half of the subarray by updating the end index to mid - 1.
   • If the target element is greater than the middle element, recursively call the binary search method on the right half of the subarray by updating the start index to mid + 1.
5. Repeat steps 3-4 until the target element is found or the subarray is exhausted (i.e., start becomes greater than end).
6. If the target element is not found, return -1 to indicate that it doesn’t exist in the array.

Here’s an example implementation of the binary search algorithm in Java:

<span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> <span class="hljs-title class_">BinarySearch</span> {
<span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-type">int</span> <span class="hljs-title function_">binarySearch</span><span class="hljs-params">(<span class="hljs-type">int</span>[] arr, <span class="hljs-type">int</span> target)</span> {
<span class="hljs-keyword">return</span> binarySearch(arr, target, <span class="hljs-number">0</span>, arr.length - <span class="hljs-number">1</span>);
}

<span class="hljs-keyword">if</span> (result == -<span class="hljs-number">1</span>) {
System.out.println(<span class="hljs-string">"Element not found in the array."</span>);
} <span class="hljs-keyword">else</span> {
System.out.println(<span class="hljs-string">"Element found at index: "</span> + result);
}
}
}


The binary search algorithm has a time complexity of O(log n), where n is the number of elements in the array. This makes it an efficient search algorithm for large sorted arrays.

Regarding the types of binary search, there are two commonly used variations:

1. Iterative Binary Search: This implementation of binary search uses a loop to perform the search. It iteratively updates the start and end indices based on the comparison with the middle element until the target element is found or the subarray is exhausted.
2. Recursive Binary Search: This implementation of binary search uses a recursive function to perform the search. It recursively calls itself with updated start and end indices until the target element is found or the subarray is exhausted. The example provided above demonstrates the recursive approach.