Java 中的 IdentityHashMap hashCode()方法

原文:https://www . geesforgeks . org/identityhashmap-hashcode-method-in-Java/

java 中的 Java . util . IdentityHashMap . hashcode()方法用于获取特定这个 identity hashmap 的哈希代码值。映射由多个存储键值对的桶组成。每个存储桶都有一个唯一的标识,当一个键值对被插入到存储桶中时,该键的 hashcode 与存储桶的标识符相匹配,如果匹配,则该对被成功存储。这就是哈希代码的工作原理。

语法:

Identity_HashMap.hashCode()

参数:该方法不接受任何参数。

返回值:方法返回地图的 hashcode 值。

下面的程序用来说明 Java . util . identity hashmap . hashcode()方法的工作原理:

程序 1: 将字符串值映射到整数键。

// Java code to illustrate the hashCode() method
import java.util.*;

public class Identity_Hash_Map_Demo {
    public static void main(String[] args)
    {

        // Creating an empty IdentityHashMap
        IdentityHashMap<Integer, String> identity_hash = 
                   new IdentityHashMap<Integer, String>();

        // Mapping string values to int keys
        identity_hash.put(10, "Geeks");
        identity_hash.put(15, "4");
        identity_hash.put(20, "Geeks");
        identity_hash.put(25, "Welcomes");
        identity_hash.put(30, "You");

        // Displaying the IdentityHashMap
        System.out.println("Initial Mappings are: "
                           + identity_hash);

        // Getting the hashcode value for the map
        System.out.println("The hashcode value of the map: "
                                + identity_hash.hashCode());
    }
}

输出:

Initial Mappings are: {10=Geeks, 30=You, 20=Geeks, 25=Welcomes, 15=4}
The hashcode value of the map: 2043437408

程序 2: 将整数值映射到字符串键。

// Java code to illustrate the hashCode() method
import java.util.*;

public class Identity_Hash_Map_Demo {
    public static void main(String[] args)
    {

        // Creating an empty IdentityHashMap
        Map<String, Integer> identity_hash = 
                    new IdentityHashMap<String, Integer>();

        // Mapping int values to string keys
        identity_hash.put("Geeks", 10);
        identity_hash.put("4", 15);
        identity_hash.put("Geeks", 20);
        identity_hash.put("Welcomes", 25);
        identity_hash.put("You", 30);

        // Displaying the IdentityHashMap
        System.out.println("Initial Mappings are: "
                           + identity_hash);

        // Getting the hashcode value for the map
        System.out.println("The hashcode value of the map: "
                                + identity_hash.hashCode());
    }
}

输出:

Initial Mappings are: {Geeks=20, Welcomes=25, You=30, 4=15}
The hashcode value of the map: 751311572

注意:相同的操作可以用不同数据类型的变化和组合的任何类型的映射来执行。