對map的key或value進行排序（升序、降序）

先定義map

Map<Integer,Integer> map = Maps.newHashMap();
map.put(2,11);
map.put(1,33);
map.put(3,22);

按key降序排序

//注意：此處初始化map時，若定義為Maps.newHashMap();會使排序失效。因HashMap本身結構是不具備排序的
        Map<Integer,Integer> descOrderKeyMap = Maps.newLinkedHashMap();
        map.entrySet().stream().sorted(Map.Entry.<Integer,Integer>comparingByKey().reversed()).forEachOrdered(e->descOrderKeyMap.put(e.getKey(),e.getValue()));
        log.info("按key降序排序：{}",descOrderKeyMap);

按key升序排序

Map<Integer,Integer> ascOrderKeyMap = Maps.newLinkedHashMap();
map.entrySet().stream().sorted(Map.Entry.comparingByKey()).forEachOrdered(e->ascOrderKeyMap.put(e.getKey(),e.getValue()));
log.info("按key升序排序：{}",ascOrderKeyMap);

按value降序排序

Map<Integer,Integer> descOrderValueMap = Maps.newLinkedHashMap();
map.entrySet().stream().sorted(Map.Entry.<Integer,Integer>comparingByValue().reversed()).forEachOrdered(e->descOrderValueMap.put(e.getKey(),e.getValue()));
log.info("按value降序排序：{}",descOrderValueMap);

按value升序排序

Map<Integer,Integer> ascOrderValueMap = Maps.newLinkedHashMap();
map.entrySet().stream().sorted(Map.Entry.comparingByValue()).forEachOrdered(e->ascOrderValueMap.put(e.getKey(),e.getValue()));
log.info("按value升序排序：{}",ascOrderValueMap);

結果如下：