我目前有一些 Java 8 代碼，如下所示 - 非常確定我可以將其合并到單個調用中，但不確定如何在 Looped 映射中將條件調用到位?？梢杂?peek() 來做到這一點嗎？或者其他 Java 8 調用？當前代碼//turn above groups into a map, grouped by ResolutionMap<Long,List<LeadChannel>> mappedUp = groups .stream() .collect( Collectors.groupingBy( channel->channel.getResolution().getId() ) );下一位根據鍵的 ID 手動轉換為字符串映射。Map<String, List<LeadChannel>> finalMap = new HashMap<String, List<LeadChannel>>();for ( Map.Entry<Long,List<LeadChannel>> entry : mappedUp.entrySet()) { if( !entry.getKey().equals( RESOLVED_STATUS ) ) { finalMap.put( "unresolved", entry.getValue() ); } else { finalMap.put( "resolved", entry.getValue() ); }}我正在嘗試這樣做： Map<String,List<LeadChannel>> mappedUp = groups .stream() .collect( Collectors.groupingBy( channel->channel.getResolution().getId() ) ).entrySet().stream().peek( if statement etc.. )
1 回答
慕村9548890
TA貢獻1884條經驗 獲得超4個贊
您似乎正在尋找的是一個條件groupingBy：
Map<String, List<LeadChannel>> finalMap = groups
.stream()
.collect(Collectors.groupingBy(channel ->
channel.getResolution().getId().equals(RESOLVED_STATUS) ?
"unresolved" : "resolved"));
或者在多個管道中，了解如何對數據進行分區，然后根據問題中共享的條件進一步映射它：
Map<Boolean, List<LeadChannel>> mappedUp = groups
.stream()
.collect(Collectors.partitioningBy(channel ->
channel.getResolution().getId().equals(RESOLVED_STATUS)));
Map<String, List<LeadChannel>> finalMap = mappedUp.entrySet().stream()
// in a similar manner you can map your current map's entries as well
.map(e -> new AbstractMap.SimpleEntry<>(e.getKey() ? "resolved" : "unresolved", e.getValue()))
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
或者正如 Holger 建議的那樣，最好使用 lambda 直接收集為
Map<String, List<LeadChannel>> finalMap = mappedUp.entrySet().stream()
.collect(Collectors.toMap(e -> e.getKey()? "resolved": "unresolved", Map.Entry::getValue))
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