---
title: "Discussion on \"Advanced HashMap Series: The equals() and hashCode() Contract\" | Hashnode"
description: "Discussion on \"Advanced HashMap Series: The equals() and hashCode() Contract\". How One Broken Rule Can Cripple Your HashMap"
url: "https://hashnode.com/posts/advanced-hashmap-series-the-equals-and-hashcode-contract/68139ace182e8f7832fcc28c"
---

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# [Advanced HashMap Series: The equals() and hashCode() Contract](https://blog.pragmaticbyharsh.com/advanced-hashmap-series-the-equals-and-hashcode-contract?utm_source=hashnode&utm_medium=feed)

How One Broken Rule Can Cripple Your HashMap

May 1, 2025 · 7 min read · blog.pragmaticbyharsh.com  
Updated May 6, 2025  
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-   [#equalsandhashcode](https://hashnode.com/tag/equalsandhashcode)
-   [#java](https://hashnode.com/tag/java)
-   [#hashmap](https://hashnode.com/tag/hashmap)
-   [#java-collections](https://hashnode.com/tag/java-collections)
-   [#system-design](https://hashnode.com/tag/system-design)
-   [#codingbestpractices](https://hashnode.com/tag/codingbestpractices)

## Written by

[Harshavardhanan](https://hashnode.com/@harshavardhan)

@harshavardhan

  
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Architect In Role. Developer by Heart

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