【stream表达式】java.lang.IllegalStateException: Duplicate key 0

目录

​​一、问题出现​​

​​ 二、问题原因​​

​​三、问题解决​​

一、问题出现

使用List转Map时报错 fgr.stream().collect(Collectors.toMap(RelationPub::getFromUid, (v) -> v))

java.lang.IllegalStateException: Duplicate key 0 (attempted merging values xxx.RelationPub@51d54aab and xxx.RelationPub@3ffa3c96)
  at java.base/java.util.stream.Collectors.duplicateKeyException(Collectors.java:133)
  at java.base/java.util.stream.Collectors.lambda$uniqKeysMapAccumulator$1(Collectors.java:180)
  at java.base/java.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:169)
  at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1654)
  at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
  at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
  at java.base/java.util.stream.ReduceOps$ReduceOp.eval（ReduceOps.java:913)
  at java.base/java.util.stream.AbstractPipeline.eval（AbstractPipeline.java:234)
  at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578)

 二、问题原因

转换时出现相同的key时报错

三、问题解决

用唯一的值作为map的key