Java IdentityHashMap containsValue()用法及代碼示例

java.util.IdentityHashMap.containsValue()方法用於檢查IdentityHashMap中的單個或多個鍵是否正在映射特定值。它使用Value作為參數，如果該值由映射中的任何鍵映射，則返回True。

用法:

Identity_HashMap.containsValue(Object Value)

參數：該方法僅使用一個Object類型的參數Value，表示應該由映射內的任何鍵檢查其映射的值。

返回值：如果檢測到值的映射，則該方法返回布爾值true，否則返回false。

以下示例程序旨在說明java.util.IdentityHashMap.containsValue()方法：

示例1:將字符串值映射到整數鍵。

// Java code to illustrate the containsValue() 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); 
  
        // Checking for the Value 'Geeks' 
        System.out.println("Is the value 'Geeks' present? " +  
                        identity_hash.containsValue("Geeks")); 
  
        // Checking for the Value 'World' 
        System.out.println("Is the value 'World' present? " +  
                        identity_hash.containsValue("World")); 
    } 
}

輸出：

Initial Mappings are: {10=Geeks, 30=You, 20=Geeks, 25=Welcomes, 15=4}
Is the value 'Geeks' present? true
Is the value 'World' present? false

示例2:將整數值映射到字符串鍵。

// Java code to illustrate the containsValue() method 
import java.util.*; 
  
public class Identity_Hash_Map_Demo { 
    public static void main(String[] args) 
    { 
  
        // Creating an empty IdentityHashMap 
        IdentityHashMap<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); 
  
        // Checking for the Value '10' 
        System.out.println("Is the value '10' present? " +  
                           identity_hash.containsValue(10)); 
  
        // Checking for the Value '30' 
        System.out.println("Is the value '30' present? " +  
                           identity_hash.containsValue(30)); 
  
        // Checking for the Value '40' 
        System.out.println("Is the value '40' present? " +  
                          identity_hash.containsValue(40)); 
    } 
}

輸出：

Initial Mappings are: {Geeks=20, Welcomes=25, You=30, 4=15}
Is the value '10' present? false
Is the value '30' present? true
Is the value '40' present? false

注意：可以對具有不同數據類型的變化和組合的任何類型的映射執行相同的操作。

相關用法

注：本文由純淨天空篩選整理自Chinmoy Lenka大神的英文原創作品 IdentityHashMap containsValue() Method in Java。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。