HashMap different hashcodes return different values? Java

Question

I have a hashmap of two objects, but it seems to return different values because the hashcode is different. Ex.

HashMap<HashMapTest, String> newMap = new HashMap<HashMapTest, String>();
    newMap.put(new HashMapTest("test"), "line");
    System.out.println(newMap.get(new HashMapTest("test")));

the hashcodes are different when I put it in the hashmap and when I get it from the hashmap. Is there any way of fixing this?

Let's see your HashMapTest class please.

weston
– weston

2012-04-21 16:37:25 +00:00
Commented Apr 21, 2012 at 16:37 — weston
– weston, Commented Apr 21, 2012 at 16:37

Community · Accepted Answer · 2017-05-23 12:03:17Z

6

Did you provide your custom implementation of the hashCode() method in HashMapTest? I guess not, and that's the default behavior of hashCode() inherited from java.lang.Object (you are actually using two different objects.) Have a look at this question to provide correct hashCode/equals implementations for your classes.

edited May 23, 2017 at 12:03

CommunityBot

11 silver badge

answered Apr 21, 2012 at 15:46

Alexander Pavlov

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