进行排序
public static void main(String[] args) { Map<String, String> map = new TreeMap<String, String>(); map.put("d", "ddddd"); map.put("c", "ccccc"); List<Map.Entry<String, String>> list = new ArrayList<Map.Entry<String, String>>(map.entrySet()); Collections.sort(list, new Comparator<Map.Entry<String, String>>() { public int compare(Map.Entry<String, String> o1, Map.Entry<String, String> o2) { return o1.getKey().compareTo(o2.getKey()); } }); String string = String.valueOf(list.get(0)) + String.valueOf(list.get(1)); System.out.println(string); }
replace with lambda
Collections.sort(list, (o1, o2) -> o1.getKey().compareTo(o2.getKey()));
replace with Comparator.comparing
Collections.sort(list, Comparator.comparing(Map.Entry::getKey));
结束