Set And Map In Java

In the arraylist chapter, you learned that arrays store items as an ordered collection, and you have to access them with an index number (int type). It provides several implementation classes such as hashmap, linkedhashmap, treemap, etc. Let’s construct a map from set of color objects using colorname as key and colorcode as value:

However, there are some differences between maps and objects. It extends the collection interface. While a map holds two objects per entry e.g.

Specifically in java, a collection refers to any group of objects stored in a single structure belonging to some class stored in java.util.

A hashmap however, store items in key/value pairs, and you can access them by an index of another type (e.g. Nothing to show {{ refname }} default. Because of this property, you can use a map () in java 8 to transform a collection, list, set, or map. So we will be accessed it by map.entry name.