Find element position in a sorted array using java's Arrays.binarySearch() function

Use Java's Arrays.binarySearch() function to find the position of an element in a sorted array

In development, you often encounter situations where you need to find the position of a specified element in a sorted array. To simplify this process, Java provides the binarySearch() function in the Arrays class. This article will introduce the use of this function in detail and give corresponding code examples.

1. Function of Arrays.binarySearch() function
The Arrays.binarySearch() function can help us quickly find the position of the specified element in the sorted array. This function uses the binary search algorithm, so it has high search efficiency. The parameters of the function include the sorted array, the element to be found, and an optional comparator (for customizing the comparison rules of the elements), and the return value is the index value of the element.

2. How to use the Arrays.binarySearch() function
Before using the Arrays.binarySearch() function, you need to ensure that the array has been sorted in ascending or descending order. When using the binarySearch() function on an unsorted array, the results are undefined.
The following is the usage and syntax of the binarySearch() function:
int binarySearch(int[] arr, int key): Find the index of the key element in the arr array, if found return the index value of the element; if If not found, a negative value is returned, indicating the position where the key should be inserted into the array.

3. Code Example
The following is a sample code that shows how to use the binarySearch() function to find the position of a specified element in a sorted integer array:

import java. util.Arrays;

public class BinarySearchExample {

public static void main(String[] args) {
    int[] arr = {2, 4, 6, 8, 10, 12, 14};
    int key = 10;
    
    int index = Arrays.binarySearch(arr, key);
    
    if (index >= 0) {
        System.out.println("元素 " + key + " 位于数组的索引 " + index + " 处。");
    } else {
        System.out.println("元素 " + key + " 不存在于数组中。");
    }
}

}

The above code first defines a sorted integer array, and then uses the binarySearch() function to search in the array Find the position of element 10. If the returned index value is greater than or equal to 0, it means that the element exists in the array, and the program outputs the corresponding prompt information; otherwise, it means that the element does not exist in the array.

4. Summary
By using Java’s Arrays.binarySearch() function, we can conveniently and efficiently find the position of a specified element in a sorted array. In actual development, this function can help us improve code execution efficiency and reduce development workload. It should be noted that before using this function, you need to ensure that the array has been sorted, otherwise the results will not meet expectations.

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