Java 集合 从HashMap删除所有映射

import java.util.HashMap;

public class RemoveAllExample {

 public static void main(String[] args) {

    // Creating a HashMap of int keys and String values
    HashMap<Integer, String> hashmap = new HashMap<Integer, String>();

    // Adding Key and Value pairs to HashMap
    hashmap.put(11,"Value1");
    hashmap.put(22,"Value2");
    hashmap.put(33,"Value3");
    hashmap.put(44,"Value4");
    hashmap.put(55,"Value5");

    // Displaying HashMap Elements
    System.out.println("HashMap Elements: " + hashmap);

    // Removing all Mapping
    hashmap.clear();

    // Displaying HashMap Elements after remove
    System.out.println("After calling clear():");
    System.out.println("---------------------");
    System.out.println("HashMap Elements: " + hashmap); 
 }
}

HashMap Elements: {33=Value3, 55=Value5, 22=Value2, 11=Value1, 44=Value4}
After calling clear():
---------------------
HashMap Elements: {}