Easily Convert a Java Enumeration Into a Stream

Converting a Java Enumeration Into a Stream

In Java, an enumeration is a construct that provides a way to store a set of related constants. An enumeration is typically used when a variable can take on one of a limited set of possible values. In many cases, it is useful to convert an enumeration into a stream, allowing it to be used more effectively in Java 8 pipelines. This article will explain how to do so.

Creating a Stream from an Enumeration

The process for converting an enumeration into a stream is fairly simple. The first step is to create a new collection containing the constants of the enumeration. This can be done using a static method of the EnumSet class. The following example illustrates this using the Flower enumeration:

    import java.util.EnumSet;

    public enum Flower {
        ROSE,
        DAISY,
        TULIP
    }

    // Create a collection containing the constants of the enumeration
    Collection flowers = EnumSet.allOf(Flower.class);

Now that a collection has been created containing the constants of the enumeration, a stream can be created from it using the stream() method of the Collection interface. The following example illustrates this using the flowers collection created above:

    // Create a stream from the collection
    Stream flowerStream = flowers.stream();

At this point, the enumeration has been successfully converted into a stream, and can now be used within Java 8 pipelines. For example, the following code demonstrates how the stream could be used to filter out all entries which are not roses:

    // Filter stream to only include roses
    Stream rosesStream = flowerStream.filter(f -> f == Flower.ROSE);

Conclusion

In this article, we have discussed how to convert a Java enumeration into a stream. We have seen how to use the EnumSet class to create a collection containing the constants of the enumeration, and how to create a stream from this collection using the stream() method. This can be incredibly useful when using Java 8 pipelines, as it allows easy manipulation of the enumeration's constants.