chapter30-data_structure.jsh

// To starts, run jshell --enable-preview which is a program able to interpret Java syntax
// then cut and paste the following lines to see how it works
// To exit jshell type /exit

// In Java, there are already plenty of data structures already available
// there are grouped under the name the collection API.

// Lists are not the only data structure in Java, you also have set, queue and map
// - a set is set where you can not store the same object twice
//   (object are the same is equals() return true)
// - a queue add or remove object at the head or at the tail of the queue
//   (so a stack is a queue, a FIFO is a queue, etc)
// - a map is a dictionary that associate a key (which is unique) to a value

// so to create an unmodifiable set, using the static method of()
var authors = Set.of("J.R.R. Tolkien", "Philip K. Dick", "George R.R. Martin");
System.out.println(authors);

// elements inside a set are organized in a way that make `contains` fast
System.out.println(authors.contains("Philip K. Dick"));

// there are 3 modifiable sets
// - HashSet
// - LinkedHashSet, as fast as set
// - TreeSet, elements are sorted

// a set has no order by default, apart if you create a LinkedHashSet