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HashMap源码分析中put的方法的流程图的疑问 #608

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zhongshanhao opened this issue Dec 31, 2019 · 4 comments
Open

HashMap源码分析中put的方法的流程图的疑问 #608

zhongshanhao opened this issue Dec 31, 2019 · 4 comments
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@zhongshanhao
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@zhongshanhao zhongshanhao commented Dec 31, 2019

图中若key存在，直接覆盖其节点值，这时不应该将size加1吧？按照源码分析应该直接返回被覆盖之前的值吧？
@LiWenGu
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@LiWenGu LiWenGu commented Dec 31, 2019

直接覆盖之后应该就会 return，不会有后续操作。这个图确实有问题。
参考 JDK8 HashMap.java 658 行
@zhongshanhao
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@zhongshanhao zhongshanhao commented Dec 31, 2019

直接覆盖之后应该就会 return，不会有后续操作。这个图确实有问题。
参考 JDK8 HashMap.java 658 行

确实，源码实现是直接返回被覆盖的值的。
@softwareCQT
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@softwareCQT softwareCQT commented Mar 29, 2020

如果是putIfAbsent的话才不会被覆盖掉，返回原来的值，主要看那个onlyIfAbsent
@hokage123
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@hokage123 hokage123 commented Jun 10, 2020

PutIfAbsent Or OnlyIfabsent serve what purpose
If Put() method work for the key if it is not present
Otherwise it overrides the value of key.
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@LiWenGu @zhongshanhao @Snailclimb @hokage123 @softwareCQT
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