Transform HashMap in Java 8

In this post, we will see how to transform HashMap key-value pairs from one Type to another Type in Java 8.


 

1. Transforming HashMap<K1, V> to HashMap<K2, V>

 

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Output:

{1=One, 2=Two, 3=Three}

 

2. Transforming HashMap<K, V1> to HashMap<K, V2>

 

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Output:

{One=1, Two=2, Three=3}

 

3. Transforming HashMap<K1, V1> to HashMap<K2, V2>

 

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Output:

{1=1, 2=4, 3=9}

 
In similar way, we can convert HashMap of other types. For instance, we can use String.valueOf() method in place of Integer.parseInt() to convert an Integer key/value to a String.

 
Thanks for reading.




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