我有一個要求，我想將地圖轉換為地圖列表。我嘗試了以下代碼，List<Map<String, Object>> response = new ArrayList<>();Set<Long> categories = new HashSet<>();List<CCP> ccpList = ccpRepository.findByPIdIn(ids);Map<Integer, List<Integer>> categoriesByProduct = ccpList.stream() .collect(Collectors.groupingBy(ccp -> ccp.getPId(), Collectors.mapping(ccp-> ccp.getCId(), Collectors.toList())));for(Entry<Integer, List<Integer>> en : categoriesByProduct.entrySet()) { Map<String,Object> responseObject = new HashMap<>(); responseObject.put("pid", en.getKey()); responseObject.put("categories",en.getValue()); response.add(responseObject);}有什么方法可以修改java 8風格的以下代碼：for(Entry<Integer, List<Integer>> en : categoriesByProduct.entrySet()) { Map<String,Object> responseObject = new HashMap<>(); responseObject.put("pid", en.getKey()); responseObject.put("categories",en.getValue()); response.add(responseObject);}
2 回答
慕桂英4014372
TA貢獻1871條經驗 獲得超13個贊
將 for-loop-content 放在一個函數中并將其與流一起使用：
response = categoriesByProduct.entrySet()
.stream()
.map(e -> toMap(e))
.collect(Collectors.toList());
public static Map<String, Object> toMap(Map.Entry<Integer, List<Integer>> en) {
Map<String,Object> responseObject = new HashMap<>();
responseObject.put("pid", en.getKey());
responseObject.put("categories",en.getValue());
return responseObject;
}
喵喔喔
TA貢獻1735條經驗 獲得超5個贊
你可以這樣做，
List<Map<String, Object>> result = categoriesByProduct.entrySet().stream()
.map(e -> Stream
.of(new AbstractMap.SimpleEntry<String, Object>("pid", e.getKey()),
new AbstractMap.SimpleEntry<String, Object>("categories", e.getValue()))
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)))
.collect(Collectors.toList());
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