In Java, the TreeMap class is a part of the java.util package and provides an implementation of the SortedMap interface. It maintains a sorted order of the elements based on their keys, which allows for efficient retrieval and traversal operations.
Under the hood, TreeMap uses a Red-Black tree data structure to store its elements. A Red-Black tree is a self-balancing binary search tree that ensures the tree remains balanced, which results in efficient time complexity for operations such as insertion, deletion, search, and retrieval.
Each element in a TreeMap is stored as a key-value pair, where the keys are unique and must be comparable (either by implementing the Comparable interface or by providing a custom Comparator). This allows TreeMap to order the elements based on their keys.
When using the default constructor of TreeMap, the keys are sorted in their natural order. For example, if the keys are of type Integer, they are sorted in ascending order. If the keys are of type String, they are sorted lexicographically.
Alternatively, you can provide a custom Comparator to the TreeMap constructor to define a specific sorting order. This allows you to sort the keys based on your own criteria, which may not be their natural order.
The put(key, value) method allows you to insert a key-value pair into the TreeMap. The element will be inserted in the proper position according to the sorting order defined by the keys.
The get(key) method returns the value associated with the given key in the TreeMap. It provides efficient retrieval as TreeMap uses a binary search tree internally, resulting in a time complexity of O(log(n)).
The remove(key) method deletes the key-value pair associated with the given key from the TreeMap, if present.
TreeMap provides methods to iterate over its elements in a sorted order. The following methods can be used for traversal:
The keySet() method returns a sorted set of all the keys in the TreeMap. You can then iterate over this set to process the elements.
The entrySet() method returns a set of all the key-value pairs in the TreeMap. Each element in this set is of type Map.Entry, which contains both the key and the corresponding value. Again, you can iterate over this set to access the elements in a sorted manner.
TreeMap is a powerful implementation of the SortedMap interface that allows for efficient storage and retrieval of elements based on key-value pairs. It uses a self-balancing binary search tree data structure to maintain a sorted order of the elements. By utilizing TreeMap, you can easily perform operations on sorted maps without worrying about manually sorting the keys.
noob to master © copyleft
noob to master