testhashmap.java

本书是一本为Java学习者在基础内容学习结束后进行课程设计时提供参考的指导书

package apibook.c2.s1;

import java.util.*;
public class TestHashMap {

  public TestHashMap() {
  }
  public static void printElem(Iterator iter){
  	//显示集合中的元素
    while(iter.hasNext()){
    	//对集合进行迭代
      System.out.println(iter.next());
    }
  }
  public static void main(String[] args) {
  	//创建一个HashMap对象
    HashMap hm1 = new HashMap(10,(float)0.75);
        //测试该HashMap对象是否为空
    if(hm1.isEmpty())System.out.println("This HashMap is Empty");
        //设置该HashMap对象中的映射
    hm1.put("key1","value1");
    hm1.put("key2","value2");
        //判断该HashMap对象中是否包含指定的键值
    if(!hm1.containsKey("key3"))System.out.println("This HashMap doesn't contains key3");
    if(!hm1.isEmpty())System.out.println("This HashMap is not Empty");
    hm1.put("key3","value3");
    hm1.put("key4","value4");
    hm1.put("key5","value5");
    if(hm1.containsKey("key3"))System.out.println("This HashMap contains key3");
    System.out.println("This HashMap's Size is:"+hm1.size());
    System.out.println("key4:"+hm1.get("key4"));
    System.out.println("---------------------------------");
    //获得该HashMap对象中的实体集
    Set s = hm1.entrySet();
    TestHashMap.printElem(s.iterator());
    System.out.println("---------------------------------");
    //删除该HashMap对象中的映射
    hm1.remove("key1");
    hm1.remove("key2");
    hm1.remove("key3");
    hm1.remove("key4");
    hm1.remove("key5");
    if(hm1.isEmpty())System.out.println("This HashMap is Empty");
  }
}