Java LinkedHashMap get()方法及示例

在Java中，LinkedHashMap类的get()方法是用来检索或获取参数中提到的特定键所映射的值。当地图中没有该键的映射时，它会返回NULL。

--> java.util Package
    --> LinkedHashMap Class
         --> get() Method  

语法

Linked_Hash_Map.get( _Object key_element_ )

参数： 一个对象类型的参数key_element，指的是要获取其相关值的钥匙。

返回类型： 与参数中key_element相关的值。

例子1： 将字符串值映射到整数键。

// Java Program to illustrate get() method
// of LinkedHashMap
// Mapping String Values to Integer Keys
  
// Importing required classes
import java.util.*;
  
// Main class
public class GFG {
  
    // Main driver method
    public static void main(String[] args)
    {
  
        // Creating an empty HashMap
        LinkedHashMap<Integer, String> li_hash_map
            = new LinkedHashMap<Integer, String>();
  
        // Mapping string values to int keys
        // using put() method
        li_hash_map.put(10, "Geeks");
        li_hash_map.put(15, "4");
        li_hash_map.put(20, "Geeks");
        li_hash_map.put(25, "Welcomes");
        li_hash_map.put(30, "You");
  
        // Printing all elements of LinkedHashMap
        System.out.println("Initial Mappings are: "
                           + li_hash_map);
  
        // Getting the value of 25
        System.out.println("The Value is: "
                           + li_hash_map.get(25));
  
        // Getting the value of 10
        System.out.println("The Value is: "
                           + li_hash_map.get(10));
    }
}

输出

Initial Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
The Value is: Welcomes
The Value is: Geeks

例2： 将整数值映射到字符串键上

// Java Program to Illustrate get() method
// Mapping Integer Values to String Keys
  
// Importing required classes
import java.util.*;
  
// Main class
public class Linked_Hash_Map_Demo {
  
    // Main driver method
    public static void main(String[] args)
    {
  
        // Creating an empty LinkedHashMap
        LinkedHashMap<String, Integer> li_hash_map
            = new LinkedHashMap<String, Integer>();
  
        // Mapping int values to string keys
        // using put() method
        li_hash_map.put("Geeks", 10);
        li_hash_map.put("4", 15);
        li_hash_map.put("Geeks", 20);
        li_hash_map.put("Welcomes", 25);
        li_hash_map.put("You", 30);
  
        // Printing all elements of LinkedHashMap
        System.out.println("Initial Mappings are: "
                           + li_hash_map);
  
        // Getting the value of "Geeks"
        System.out.println("The Value is: "
                           + li_hash_map.get("Geeks"));
  
        // Getting the value of "You"
        System.out.println("The Value is: "
                           + li_hash_map.get("You"));
    }
}

输出

Initial Mappings are: {Geeks=20, 4=15, Welcomes=25, You=30}
The Value is: 20
The Value is: 30

注意： 同样的操作可以通过不同数据类型的变化和组合对任何类型的Mapping进行操作。