Utilisation et exemple de la méthode hashCode() de String dans Java

Java String (string) methods

La méthode hashCode() de String dans Java renvoie le code hash de la chaîne.

La syntaxe de la méthode hashCode() de la chaîne de caractères est :

string.hashCode()

ici, string est un objet de la classe String.

paramètre de hashCode()

• sans aucun paramètre

valeur de hashCode()

• Return the hash code of the string, which is an int value
  

The hash code is calculated using the following formula:

s[0]*31(n-1)　+　s[1]*31(n-2)　+　...　+　s[n-1]

where

• s[0] is the first element of the string s, s[1is the second element, and so on.

• n - is the length of the string

Example: Java string hashCode()

class Main {
　　public static void main(String[] args) {
　　　　String str1　= "Java";
　　　　String str2　= "Java Programming";
　　　　String str3　= "";
　　　　System.out.println(str1.hashCode());　//　2301506
　　　　System.out.println(str2.hashCode());　//　1377009627
　　　　//　hash code of empty string is 0
　　　　System.out.println(str3.hashCode());　//　0
　　}
}

The hash code is a number generated from any object (the memory address of the object), not just a string. This number is used to quickly store in the hash table/Retrieve the object.

For two strings to be equal, their hash codes must also be equal.

Java String (string) methods