Difference between Pair and Hashmap?
Solution 1
Your choice of which class to use is not just a message to your computer. It's also a message to future developers - people who will maintain your code in the future, or even you yourself in a few months time.
By choosing whether to declare a particular variable as either HashMap
or Pair
, you're telling those future developers something. It's EITHER
This variable references some kind of map, which uses a hash algorithm for fast retrieval.
OR
This variable references a pair of values.
That will help the future developers to understand what your code is doing. Whereas you can certainly use a HashMap
with a single entry instead of a Pair
, it would be a very strange thing to do, and it would send entirely the wrong message to the future maintainers of your code.
Solution 2
A pair is basically a convenient way of associating a simple key to a value. Maps do the same thing to store key-value pairs but maps stores a collection of pairs and operate them as a whole.
Number of times we have a requirement where a key-value pair shall exist on its own, for instance:
- A key-value pair needs to be passed to a method as an argument, Or
- A method needs to return just two values in form of a pair
Map complicates the things when we just need a single pair of key-value.
![Mani](https://i.stack.imgur.com/hXeV9.png?s=256&g=1)
Comments
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Mani about 2 years
What is the necessity to introduce Pair class when Hashmap can do the same job?
I see Pair being introduced to Java version 8