map有自带的排序功能,但需要重写排序方法,代码如下:
package coreJava.com.shindo.corejava.map; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Map.Entry; public class MapSort { /** * * @Title: sortMap * @Description: 对集合内的数据按key的字母顺序做排序 */ public List<Map.Entry<String, String>> sortMap(final Map<String, String> map) { final List<Map.Entry<String, String>> infos = new ArrayList<Map.Entry<String, String>>(map.entrySet()); // 重写集合的排序方法:按字母顺序 Collections.sort(infos, new Comparator<Map.Entry<String, String>>() { @Override public int compare(final Entry<String, String> o1, final Entry<String, String> o2) { return (o1.getKey().toString().compareTo(o2.getKey())); } }); return infos; } public static void main(final String[] args) { final Map<String, String> map = new HashMap<String, String>(); map.put("charSet", "utf-8"); map.put("merId", "5412"); map.put("acqId", "321"); final List<Map.Entry<String, String>> list = new MapSort().sortMap(map); for (final Map.Entry<String, String> m : list) { System.out.println(m.getKey() + ":" + m.getValue()); } } }
执行main方法,结果如下:
acqId:321 charSet:utf-8 merId:5412