hashmap,使用iterator读取后顺序改变

public LinkedHashMap<String, String> ReadDistrictAndCity() {
 
 
 LinkedHashMap<String, String> map = new LinkedHashMap<String, String>();
 
 
 SAXReader reader = new SAXReader();
 
 
 Document doc = null;
 
 
 try {
 
 
 InputStream in = getClass().getClassLoader().getResourceAsStream(
 
 
 "district-city.xml");
 
 
 doc = reader.read(in);
 
 
 } catch (DocumentException e1) {
 
 
 e1.printStackTrace();
 
 
 }
 
 
 Element RECORDS = doc.getRootElement();
 
 
 Element foo = null;
 
 
 for (Iterator i = RECORDS.elementIterator("RECORD"); i.hasNext();) {
 
 
 foo = (Element) i.next();
 
 
 // System.out.println(foo.elementText("CITY").toString()+"___"+foo.elementText("DISTRICT").toString());
 
 
 map.put(foo.elementText("CITY").toString(), foo.elementText(
 
 
 "DISTRICT").toString());
 
 
 }
 
 
 return map;
 
 
 }

采用LinkedHashMap读取后顺序不会乱

hashmap类是散列映射并不保证它的元素顺序．因此，元素加入散列映射的顺序并不一定是它们被迭代函数读出的顺序，如果想要保持顺序的话可以使用LinkedHashMap，可以保证迭代输出的顺序和输入的一样