Groovy - Maps

A Map (also known as an associative array, dictionary, table, and hash) is an unordered collection of object references. The elements in a Map collection are accessed by a key value. The keys used in a Map can be of any class. When we insert into a Map collection, two values are required: the key and the value.

Following are some examples of maps −

  • [‘TopicName’ : ‘Lists’, ‘Author’ : ‘Raghav’] – Collections of key value pairs which has TopicName as the key and their respective values.

  • [ : ] – An Empty map.

In this chapter, we will discuss the map methods available in Groovy.

Sr.No. Methods & Description
1 containsKey()

Does this Map contain this key?

2 get()

Look up the key in this Map and return the corresponding value. If there is no entry in this Map for the key, then return null.

3 keySet()

Obtain a Set of the keys in this Map.

4 put()

Associates the specified value with the specified key in this Map. If this Map previously contained a mapping for this key, the old value is replaced by the specified value.

5 size()

Returns the number of key-value mappings in this Map.

6 values()

Returns a collection view of the values contained in this Map.