markdown Java Colletion常用代码

Posted 2021-05-05

## Map
```java
//Map按照value升序排序
Map<String, Integer> sorted = budget
    .entrySet()
    .stream()
    .sorted(comparingByValue())
    .collect(toMap(e -> e.getKey(), e -> e.getValue(), (e1, e2) -> e2, LinkedHashMap::new));

//Map按照value降序排序
Map<String, Integer> sorted = budget
    .entrySet()
    .stream()
    .sorted(Collections.reverseOrder(Map.Entry.comparingByValue()))
    .collect(toMap(Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e2, LinkedHashMap::new));

//List -> Map
Map<Integer, String> result1 = list.stream().collect(Collectors.toMap(Hosting::getId, Hosting::getName));
```