Map

1.遍历key，value

• Set

Map<String, String> fieldsMap = new HashMap<>();
Set<String> keySet = fieldsMap.keySet();
for (String key : keySet) {
  System.out.println(key + " " + fieldsMap.get(key));
}

• Iterator

Iterator iterator = keyset.iterator();
while(iterator.hasNext()){
    Object key = iterator.next();
    System.out.println(key+"-"+hashMap.get(key));
}

• entrySet()

Set set = hashMap.entrySet();
for(Object key:set){
    Map.Entry entry = (Map.Entry) key;
    System.out.println(entry.getKey()+"-"+entry.getValue());
}

• Map.Entry

Set set1 = hashMap.entrySet();
Iterator iterator1 = set1.iterator();
while(iterator1.hasNext()){
    Object itset = iterator1.next();
    Map.Entry entry = (Map.Entry) itset;
    System.out.println(entry.getKey()+"-"+entry.getValue());
}