How to merge two HashMap in Java 8 - Map.merge() example

Hello guys, if you are wondering how to merge two Map like two HashMap in Java then you have come to the right place. In this tutorial,  I will show you step by step to merge two HashMap in Java. You can merge two Map in Java using the newly added merge() function in Java 8. This allows you to copy values from one map to another to merge both of them. It also provide a lot of flexibility to handle duplicate keys. In the last article, I have shown you how to combine two Map in Java using the putAll() method but there was a problem. If a key is present in both maps, then putAll() overrides the value from the second map, which you may or may not want.