I need something like a 3-dimension (like a list or a map), which I fill with 2 Strings and an Integer within a loop. But, unfortunately I don’t know which data structure to use and how. Answer Create an object that encapsulates the three together and add them to an array or List: If you want to insert …
Tag: dictionary
Find element position in a Java TreeMap
I am working with a TreeMap of Strings TreeMap<String, String>, and using it to implement a Dictionay of words. I then have a collection of files, and would like to create a representation of each file in the vector space (space of words) defined by the dictionary. Each file should have a vector represe…
When to use a Map instead of a List in Java?
I didn’t get the sense of Maps in Java. When is it recommended to use a Map instead of a List? Answer Java map: An object that maps keys to values. A map cannot contain duplicate keys; each key can map to at most one value. Java list: An ordered collection (also known as a sequence). The user of this
What’s the difference between ConcurrentHashMap and Collections.synchronizedMap(Map)?
I have a Map which is to be modified by several threads concurrently. There seem to be three different synchronized Map implementations in the Java API: Hashtable Collections.synchronizedMap(Map) ConcurrentHashMap From what I understand, Hashtable is an old implementation (extending the obsolete Dictionary cl…