package com.sf.day17; import org.junit.Test; import java.util.HashMap; import java.util.Map; public class Test01 { @Test public void t1(){ Map map = new HashMap(); map.put("username","zhangsan"); map.put("username1","zhangsan"); map.put("username2","zhangsan"); map.put("username3","zhangsan"); for (Map.Entry entry : map.entrySet()) { System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue()); } } }