📜  Java中的 IdentityHashMap clear() 方法

📅  最后修改于: 2022-05-13 01:55:22.124000             🧑  作者: Mango

Java中的 IdentityHashMap clear() 方法

Java中的Java .util.IdentityHashMap.clear() 方法用于清除和删除指定映射中的所有元素或映射。

句法:

Identity_HashMap.clear()

参数:该方法不接受任何参数。

返回值:该方法不返回任何值。

以下程序用于说明Java.util.IdentityHashMap.clear() 方法的工作:

程序 1:将字符串值映射到整数键。

// 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 identity_hash = new IdentityHashMap();
  
        // 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);
    }
}
输出:
Initial Mappings are: {10=Geeks, 30=You, 20=Geeks, 25=Welcomes, 15=4}
Final Map: {}

程序 2:将整数值映射到字符串键。

// 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 identity_hash = new IdentityHashMap();
  
        // 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);
    }
}
输出:
Initial Mappings are: {Geeks=20, Welcomes=25, You=30, 4=15}
Final Map: {}

注意:可以使用任何类型的映射执行相同的操作,其中包含不同数据类型的变化和组合。