Java IdentityHashMap clear()用法及代碼示例

Java中的java.util.IdentityHashMap.clear()方法用於清除和刪除指定映射中的所有元素或映射。

用法:

Identity_HashMap.clear()

參數：該方法不接受任何參數。

返回值：該方法不返回任何值。

以下程序用於說明java.util.IdentityHashMap.clear()方法的用法：

示例1:將字符串值映射到整數鍵。

// Java code to illustrate the clear() 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); 
  
        // Clearing the map using clear() 
        identity_hash.clear(); 
  
        // Displaying the final IdentityHashMap 
        System.out.println("Final Map: "
                           + identity_hash); 
    } 
}

輸出：

Initial Mappings are: {10=Geeks, 30=You, 20=Geeks, 25=Welcomes, 15=4}
Final Map: {}

示例2:將整數值映射到字符串鍵。

// Java code to illustrate the clear() 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); 
  
        // Clearing the map using clear() 
        identity_hash.clear(); 
  
        // Displaying the final IdentityHashMap 
        System.out.println("Final Map: "
                           + identity_hash); 
    } 
}

輸出：

Initial Mappings are: {Geeks=20, Welcomes=25, You=30, 4=15}
Final Map: {}

注意：可以對具有不同數據類型的變體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 clear() 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。