https://www.cnblogs.com/binz/p/6671917.html
一、根据value排序
通用方法
public class MapUtil {
public static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(Map<K, V> map) {
List<Map.Entry<K, V>> list = new LinkedList<Map.Entry<K, V>>(map.entrySet());
Collections.sort(list, new Comparator<Map.Entry<K, V>>() {
public int compare(Map.Entry<K, V> o1, Map.Entry<K, V> o2) {
return (o1.getValue()).compareTo(o2.getValue());
}
});
Map<K, V> result = new LinkedHashMap<K, V>();
for (Map.Entry<K, V> entry : list) {
result.put(entry.getKey(), entry.getValue());
}
return result;
}
}
java7
public static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(Map<K, V> map) {
List<Map.Entry<K, V>> list = new LinkedList<>(map.entrySet());
Collections.sort(list, new Comparator<Map.Entry<K, V>>() {
@Override
public int compare(Map.Entry<K, V> o1, Map.Entry<K, V> o2) {
return (o1.getValue()).compareTo(o2.getValue());
}
});
Map<K, V> result = new LinkedHashMap<>();
for (Map.Entry<K, V> entry : list) {
result.put(entry.getKey(), entry.getValue());
}
return result;
}
public static Map<String, String> sortMapByValue(Map<String, String> oriMap) {
if (oriMap == null || oriMap.isEmpty()) {
return null;
}
Map<String, String> sortedMap = new LinkedHashMap<String, String>();
List<Map.Entry<String, String>> entryList = new ArrayList<Map.Entry<String, String>>(
oriMap.entrySet());
Collections.sort(entryList, new Comparator<Map.Entry<String, String>> {
@Override
public int compare(Entry<String, String> me1, Entry<String, String> me2) {
return me1.getValue().compareTo(me2.getValue());
}
});
Iterator<Map.Entry<String, String>> iter = entryList.iterator();
Map.Entry<String, String> tmpEntry = null;
while (iter.hasNext()) {
tmpEntry = iter.next();
sortedMap.put(tmpEntry.getKey(), tmpEntry.getValue());
}
return sortedMap;
}
java8
public static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(Map<K, V> map) {
Map<K, V> result = new LinkedHashMap<>();
Stream<Entry<K, V>> st = map.entrySet().stream();
st.sorted(Comparator.comparing(e -> e.getValue())).forEach(e -> result.put(e.getKey(), e.getValue()));
return result;
}
二、根据key排序
public static Map<String, String> sortMapByKey(Map<String, String> map) {
if (map == null || map.isEmpty()) {
return null;
}
Map<String, String> sortMap =
new TreeMap<>(Comparator.naturalOrder());
// new TreeMap<>((str1, str2) -> str1.compareTo(str2));
sortMap.putAll(map);
return sortMap;
}