Comparing Two Hashmaps in Java

Question

What's the recommended approach for comparing hashmaps in Java for equality so that I can determine if they have identical keys and values?

Map<String,List<String>> data1 = new HashMap<>();
data1.put("file1", Arrays.asList("one","two","three"));

Map<String,List<String>> data2 = new HashMap<>();
data2.put("file1", Arrays.asList("one","two","three"));

[`Map.equals()`](https://docs.oracle.com/javase/8/docs/api/java/util/AbstractMap.html#equals-java.lang.Object-) — Sharon Ben Asher, Aug 13 '19 at 20:24
The question may have some other considerations, like: what is more efficient (faster)? If the keys are identical, does it mean the values are implied? more docs: https://howtodoinjava.com/java/collections/hashmap/compare-two-hashmaps/ — azbarcea, Aug 13 '19 at 20:28

score 0 · Answer 1 · answered Aug 13 '19 at 20:25

0

By default, HashMap.equals() method compares two hashmaps by key-value pairs. It means both hashmap instances must have exactly same key-value pairs and both must be of same size.

answered Aug 13 '19 at 20:25

Valdrinium

1,398
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score 0 · Answer 2 · answered Aug 13 '19 at 20:25

0

Just use equals method.

boolean equals = data1.equals(data2);

answered Aug 13 '19 at 20:25

nishantc1527

376
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Comparing Two Hashmaps in Java

2 Answers2