Java uses the binarySearch() function of the Arrays class to implement binary search

Java uses the binarySearch() function of the Arrays class to implement binary search

Binary search is an efficient search algorithm that can quickly locate the target element in an ordered array. In Java, we can use the binarySearch() function of the Arrays class to implement binary search.

The Arrays class is a tool class provided in Java for operating arrays. It contains various methods for operating on arrays, including binary search. Let's take a look at how to use the binarySearch() function to implement binary search.

First, we need to create an ordered array. This array can be a basic type array or a reference type array. Here we take an integer array as an example:

int[] arr = {1, 3, 5, 7, 9, 11, 13};

Next, we call the Arrays class The binarySearch() function performs binary search. This function needs to pass in two parameters: the array to be searched and the target element to be searched. This function returns the index position of the target element in the array, or a negative number if the target element cannot be found. We can determine whether the target element is in the array by judging the positive or negative value of the return value.

int target = 9;
int index = Arrays.binarySearch(arr, target);

If the target element exists in the array, index is the index position of the target element in the array ; If the target element does not exist in the array, index is the position where the target element should be inserted minus one.

Next, we can perform corresponding processing based on the returned index. The following is a complete sample code:

import java.util.Arrays;

public class BinarySearchExample {

public static void main(String[] args) {
    int[] arr = {1, 3, 5, 7, 9, 11, 13};
    int target = 9;
    int index = Arrays.binarySearch(arr, target);
    
    if (index >= 0) {
        System.out.println("目标元素在数组中的位置是：" + index);
    } else {
        System.out.println("目标元素不存在于数组中，它应该插入的位置是：" + (-index-1));
    }
}

}

Run the above code and output The result is "The position of the target element in the array is: 4", which means that the index position of the target element 9 in the array is 4.

Binary search is an efficient search algorithm with a time complexity of O(logN), which is much faster than a simple linear search. When searching large-scale ordered arrays, using the binarySearch() function of the Arrays class can provide more efficient performance.

But it should be noted that the prerequisite for using the binarySearch() function to perform binary search is that the array must be ordered. If the array is unordered, we need to sort the array first and then perform a binary search.

To summarize, this article introduces the method of using the binarySearch() function of the Arrays class to implement binary search in Java, and provides a sample code. By mastering the principles and usage of binary search, we can find the target element in an ordered array more efficiently.

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