Three methods of map traversal

public static void main(String args[]) {
  
  

        Map<String, Object> map = Maps.newHashMap();
        map.put("a","a1");
        map.put("b","b1");
        map.put("c","c1");

    //The first
     for (String key:map.keySet()){
        System.out.println(map.get(key));
    }
    Iterator<String> it1 = map.keySet().iterator();
    while (it1.hasNext()){
        System.out.println( map.get(it1.next())+ "----------it1");;
    }

    //Second
     System. out .println( "=========================" );
     for (Object s:map.values() ){
        System.out.println(s + "-------map.values()");
    }
    Iterator<Object> itVa = map.values().iterator();
    while (itVa.hasNext()){
        System.out.println( itVa.next()+ "----------itVa");;
    }
    //第三种
    System.out.println("=========================");
    for (Map.Entry<String, Object> map1:map.entrySet()){
        System.out.println(map1.getValue() +"------map.entrySet()");
    }
    Iterator<Map.Entry<String, Object>> it = map.entrySet().iterator();
    while(it.hasNext()){
        Map.Entry<String, Object> next = it.next();
        System.out.println(next.getValue() + "-------map.values()");
    }

}

result:

b1
c1
a1
b1----------it1
c1----------it1
a1----------it1
=========================
b1-------map.values()
c1-------map.values()
a1-------map.values()
b1----------itVa
c1----------itVa
a1----------itVa
=========================
b1------map.entrySet()
c1------map.entrySet()
a1------map.entrySet()
b1-------map.values()
c1-------map.values()
a1-------map.values()