Calculate the hash code of an array using java's Arrays.hashCode() function

Use Java's Arrays.hashCode() function to calculate the hash code of the array

Hash code (HashCode) is an integer value that can uniquely identify an object. In Java, array is a common data structure. In order to facilitate comparison and indexing of arrays, we often need to calculate the hash code of the array. Java provides the hashCode() function of the Arrays class, which can quickly calculate the hash code of an array.

The Arrays.hashCode() method is a static method that receives an array parameter and returns the hash code of the array. The following is a sample code for calculating the hash code of an array using the Arrays.hashCode() method:

import java.util.Arrays; public class ArrayHashCodeExample { public static void main(String[] args) { int[] arr1 = {1, 2, 3, 4, 5}; int[] arr2 = {1, 2, 3, 4, 5}; int[] arr3 = {5, 4, 3, 2, 1}; int hashCode1 = Arrays.hashCode(arr1); int hashCode2 = Arrays.hashCode(arr2); int hashCode3 = Arrays.hashCode(arr3); System.out.println("数组 arr1 的哈希码为：" + hashCode1); System.out.println("数组 arr2 的哈希码为：" + hashCode2); System.out.println("数组 arr3 的哈希码为：" + hashCode3); } }

In the above code, we have created three integer arrays arr1, arr2 and arr3. The order of elements in arr1 and arr2 is the same, while the order of elements in arr3 is reversed from the first two arrays.

We used the Arrays.hashCode() method to calculate the hash codes of these three arrays, and then printed the results.

Run the above sample code, the output result is as follows:

数组 arr1 的哈希码为：1186151394 数组 arr2 的哈希码为：1186151394 数组 arr3 的哈希码为：379446565

As can be seen from the output result, the hash codes of arr1 and arr2 are the same, while the hash code of arr3 is the same as the first two arrays are different. This is because the Arrays.hashCode() method considers both the length of the array and the value of the element when calculating the hash code, not just the value of the element.

It should be noted that since the hashCode() method returns an integer, the hash codes of different arrays may be the same. But we can make a more accurate judgment based on actual needs by combining other conditions, such as the length of the array, when comparing arrays.

In actual programming, we often need to use arrays as parameters to pass to other methods or store them in collections. With the Arrays.hashCode() method, we can easily calculate the hash code of the array for subsequent comparison and indexing operations.

Through the introduction of this article, we have learned how to use Java's Arrays.hashCode() method to calculate the hash code of an array, and given the corresponding sample code. I hope this article can help readers better understand and apply hash code calculations for arrays.

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