Difference between arraylist and hashmap
Here we are going to learn difference between arraylist and hashmap or arraylist vs hashmap with example.
ArrayList vs HashMap differ based on following parameters:
1. Approach
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ArrayList stores only the value of the element.
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HashMap applies different mechanism as it stores value of the element along with a unique keyassociated to the stored value.
2. Memory requirement
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As ArrayList only stores the value of the element so it requires less memory space in comparision to HashMap.
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On other hand HashMap needs to store a unique key for each value so memory requirement increases.
3. Implementation
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ArrayList implements List interface.
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HashMap implements Map interface.
4. Order maintainence
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ArrayList ensures that the insertion order is maintained.
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HashMap doesn’t guarantee of maintaining insertion order (if you care about order, use LinkedHashMap).
*In case where insertion order is maintained we get the elements returned in same order in which they were inserted while retrieving them.
5. Null value
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Any number of null values can be stored in ArrayList.
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Only one null key is allowed in HashMap. But you can store any number of null values.
6. Duplicate value
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ArrayList accepts duplicate values while storing.
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HashMap doesn’t accept duplicate Key. But duplicate values are allowed.
7. Retrieve element
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In ArrayList elements can be retrieved specifying index of the element.
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In HashMap elements can be retrieved by specifying its Key.
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About the Author
Rohanjit Kumar
Technology geek, loves to write and share knowledge with the world. Having 9+ years of IT experience. B.Tech in Computer Science & Engineering
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Published Date :
Jun 28,2020
