Feb 7, 2013 · I'd like to create a map that contains entries consisting of (int, Point2D) How can I do this in Java? I tried the following unsuccessfully. HashMap hm = new HashMap(); hm.put(1, …

Java 9 added a series of Map.of static methods to do just what you want: Instantiate an immutable Map using literal syntax. The map (a collection of entries) is immutable, so you cannot add or …

Is there an object in Java that acts like a Map for storing and accessing key/value pairs, but can return an ordered list of keys and an ordered list of values, such that the key and value lists ar...

Sep 30, 2013 · The java.util.Collections class allows me to make collection instances unmodifiable. The following method protected Map<String, List<String>> getCacheData () { …

List differs from Map in the conceptual way -- Map have notion of 'key, value' pair, whereas List doesn't. Given this it's unclear how exactly you going to convert from List to Map and back.

4 I am new to Java and I'm trying to make a 2D text-based game that internally consists of a world map on which objects can interact and move. However, I'm already confused at the very …

Java 7+ contains a new Map.Entry<K,V> class that you can use as key for your map (or entry for your set). Java 9+ also contains a Map.entry(K k, V v) method to easily create new Map.Entry …

Feb 3, 2009 · How would you initialise a static Map in Java? Method one: static initialiser Method two: instance initialiser (anonymous subclass) or some other method? What are the pros and …

Jun 24, 2010 · 433 I'd like to create new item that similarly to Util.Map.Entry that will contain the structure key, value. The problem is that I can't instantiate a Map.Entry because it's an …

Jul 9, 2021 · map.put("AAA", innerMap); But as of Java 8 you can create the map as a value if it doesn't exist which is then returned using computeIfAbsent If the value (i.e. map) doesn't exist …