Prev Next

Java / Map and its implementations

Explain NavigableMap in Java collection.

NavigableMap Map was added in Java 1.6 that provides navigation capability to Map data structure. It provides methods such as lowerKey() to get keys which is less than specified key, floorKey() to retrieve keys which is less than or equal to specified key, ceilingKey() to get keys which is greater than or equal to specified key and higherKey() to return keys which is greater specified key from a Map.

Similarly navigable methods lowerEntry(), floorEntry(), ceilingEntry() and higherEntry() are available to retrieve map entries.

In addition to the navigation methods, it also enables creating sub-Map, for example, creating a Map from entries of an existing Map using tailMap, headMap and subMap. headMap() method returns a NavigableMap whose keys are less than specified, tailMap() returns a NavigableMap whose keys are greater than the specified and subMap() gives a NavigableMap between a range, specified by toKey to fromKey.

More Related questions...

List the differences between HashTable and HashMap in Java collections. Similarities between HashMap and HashTable in Java. What is a resource bundle in Java? What is the Big-O notation for operations in a Hashmap? Is HashMap faster compared to ArrayList in terms of search? Difference between HashMap and ConcurrentHashMap. Is ConcurrentHashmap good for frequently updating concurrent data structure? What are the commonly used implementations of Map in Java? Difference between Collections.synchronizedMap(Map) and ConcurrentHashMap. Difference between Collections.synchronizedMap and Hashtable. Why is ConcurrentHashMap faster than Hashtable in Java? What are the different Reference types available in Java? Which methods you need to override to use an object as key in HashMap ? Why Map does not extend the Collection interface in Java Collections Framework? How Remove method works internally in Java HashMap? Explain NavigableMap in Java collection. Explain rehashing process in Java HashMap. How null key is handled in HashMap? What is the data-structure behind the Java HashMap implementation? Why are immutable objects in HashMap so effective? Why null is not allowed in ConcurrentHashmap? Does ConcurrentHashMap allow null keys and null values ? Difference between remove() and clear() methods in HashMap. Is hashcode method invoked internally when calling get and put method in Java? How hash collision is handled in HashMap? What are the interfaces that TreeMap implements? What interfaces that HashMap implements? Big O notation for TreeMap in Java. Is TreeMap synchronized in Java? Does TreeMap allow null key? Key object constraints on a TreeMap. Does IdentityHashMap use hashcode method? Does EnumMap allow null key? What design pattern that Collections.synchronizedMap implement? Difference between HashMap and IdentityHashMap. What is a ConcurrentSkipListMap? How do you sort a TreeMap by comparing its value? Default initial table size of ConcurrentHashMap. Does Map implement Iterable?
Show more question and Answers...

Set and its implementations

Comments & Discussions

Interviews Questions

About Javapedia.net

Javapedia.net is for Java and J2EE developers, technologist and college students who prepare of interview. Also this site includes many practical examples.

This site is developed using J2EE technologies by Steve Antony, a senior Developer/lead at one of the logistics based company.

Follow Javapedia updates

contact: javatutorials2016[at]gmail[dot]com

Kindly consider donating for maintaining this website. Thanks.

Copyright © 2026, javapedia.net, all rights reserved. · .

DMCA.com Protection Status