Java MapTag ArchiveSubscribe

Apache Commons Collections OrderedMap 1. Overview The Apache Commons Collections library provides useful classes that complement the Java Collections Framework. In this article, we will review the interface OrderedMap, which extends java.util.Map. 2. Maven Dependency The first thing we need to do is to add the Maven dependency in our… Continue Reading apache-commons-ordered-map

Sort a HashMap in Java 1. Introduction In this quick tutorial, we’ll learn how to sort a HashMap in Java. More specifically, we’ll look at sorting HashMap entries by their key or value using: TreeMap ArrayList and Collections.sort() TreeSet Using the Stream API, and finally, Using the Guava library 2. Using a TreeMap… Continue Reading java-hashmap-sort

How to Store Duplicate Keys in a Map in Java? 1. Overview In this tutorial, we’re going to explore the available options for handling a Map with duplicate keys or, in other words, a Map which allows storing multiple values for a single key. 2. Standard Maps Java has several… Continue Reading java-map-duplicate-keys

Copying a HashMap in Java 1. Overview In this tutorial, we’ll explore the concept of a shallow vs deep copy of a HashMap along with several techniques to copy a HashMap in Java. We’ll also consider some of the external libraries that can help us in specific cases. 2. Shallow… Continue Reading java-copy-hashmap

Guide to WeakHashMap in Java 1. Overview In this article, we will be looking at a WeakHashMap from the java.util package. In order to understand the data structure, we’ll use it here to roll out a simple cache implementation. However, keep in mind that this is meant to understand how… Continue Reading java-weakhashmap

Differences Between HashMap and Hashtable 1. Overview In this short tutorial, we are going to focus on the core differences between the Hashtable and the HashMap. 2. Hashtable and HashMap in Java Hashtable and HashMap are quite similar – both are collections that implement the Map interface. Also, the put(), get(), remove(), and containsKey() methods provide constant-time… Continue Reading hashmap-hashtable-differences

How to Check If a Key Exists in a Map 1. Overview In this brief tutorial, we’ll look at ways to check if a key exists in a Map. Specifically, we’ll focus on containsKey and get. 2. containsKey If we take a look at the JavaDoc for Map#containsKey: Returns true if this map contains a mapping… Continue Reading java-map-key-exists

Map to String Conversion in Java 1. Overview In this tutorial, we’ll focus on conversion from a Map to a String and the other way around. First, we’ll see how to achieve these using core Java methods, and afterward, we’ll use some third-party libraries. 2. Basic Map Example In all… Continue Reading java-map-to-string-conversion