Java-Map-Programs Archives

Last Updated: 02 June 2023

Map size() method in Java is used to get the total number entries i.e, key-value pair. So this method is useful when you want total entries present on the map. If the map ...read more

Java

Java-Collections

java-map

Java-Map-Programs

How to find the Entry with largest Key in a Java Map

Last Updated: 19 July 2022

Given a map in Java, the task is to find out the entry in this map with the highest key. Examples:Input: Map = {ABC = 10, DEF = 30, XYZ = 20}Output: XYZ = 20Input: Map = {...read more

Java

java-map

Java-Map-Programs

How to Clone a Map in Java

Last Updated: 21 January 2019

Given a map, the task is to clone that map.Following are the 5 different ways to Clone a Map in Java.Example:{1=Geeks, 2=For, 3=Geeks} Method 1: Naive method1. Create a...read more

Difference Between ArrayList and HashMap in Java

Last Updated: 20 January 2022

ArrayList is a part of the collection framework and is present in java.util package. It provides us with dynamic arrays in Java. Though, it may be slower than standard arr...read more

Technical Scripter 2018

Java-List-Programs

Java-Map-Programs

How to create a TreeMap in reverse order in Java

Last Updated: 25 October 2019

By default TreeMap elements in Java are sorted in ascending order of keys. However, we can create the TreeMap in reverse order using Collections.reverseOrder() method in J...read more

How to check if a key exists in a HashMap in Java

Last Updated: 11 December 2018

Given a HashMap and a key in Java, the task is to check if this key exists in the HashMap or not.Examples:Input: HashMap: {1=Geeks, 2=ForGeeks, 3=GeeksForGeeks}, key = 2Ou...read more

Difference between HashMap and HashSet

Last Updated: 06 April 2023

HashSet is an implementation of Set Interface which does not allow duplicate value. The main thing is, objects that are stored in HashSet must override equals() for check ...read more

Program to Convert List to Map in Java

Last Updated: 19 June 2019

The List is a child interface of Collection. It is an ordered collection of objects in which duplicate values can be stored. Since List preserves the insertion order, it a...read more

Technical Scripter 2018

Java-List-Programs

Java-Map-Programs

Sort elements by frequency | Set 5 (using Java Map)

Last Updated: 01 February 2023

Given an integer array, sort the array according to the frequency of elements in decreasing order, if the frequency of two elements are same then sort in increasing orderE...read more

Arrays

Java

Analysis of Algorithms

Sorting

Hash

Advanced Data Structure

Technical Scripter

Technical Scripter 2018

Java-Map-Programs

DSA

Using TreeMap to sort User-defined Objects in Java

Last Updated: 11 December 2018

Given example shows how to sort user defined objects TreeMap, you can sort the keys based on the logic provided inside the method.Given a record of employees name and sala...read more

Java

java-TreeMap

Java-Map-Programs

Program to Convert HashMap to TreeMap in Java

Last Updated: 01 October 2021

HashMap is a part of Java’s collection since Java 1.2. It provides the basic implementation of Map interface of Java which stores the data in (Key, Value) pairs. To access...read more

Immutable Map in Java

Last Updated: 03 March 2023

ImmutableMap, as suggested by the name, is a type of Map which is immutable. It means that the content of the map are fixed or constant after declaration, that is, they ar...read more

Count occurrences of elements of list in Java

Last Updated: 31 May 2022

Suppose we have an elements in ArrayList, we can count the occurrences of elements present in a number of ways.HashMapThis data structure uses hash function to map similar...read more

Difference between HashMap and ConcurrentHashMap

Last Updated: 06 August 2019

HashMap is the Class which is under Traditional Collection and ConcurrentHashMap is a Class which is under Concurrent Collections, apart from this there are various differ...read more

Sorting a HashMap according to keys in Java

Last Updated: 14 April 2025

We are given the details of marks scored by students in form of a HashMap, where the name of the student is the Key and the marks scored is the Value. Our task is to sort ...read more