Java 8 Map Function Examples

The map is a well known functional programming concept which is incorporated into Java 8. Map is a function defined in java.util.stream.Streams class, which is used to transform each element of the stream. Because of this property, you can use Map in Java 8 to transform a Collection, List, Set or Map. For example, if you have a list of String and you want to convert all of them into upper case, how will you do this? Prior to Java 8, there is no function to do this. You had to iterate through List using a for loop or foreach loop and transform each element. In Java 8, you get the stream, which allow you to apply many functional programming operators like the map, reduce and filter. By using Map function, you can apply any function to every element of Collection. It can be any predefined function or a user-defined function. You not only can use the lambda expression but also, you can also use method references.

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