Tutorial by Examples

First, we create an empty map, and insert some elements into it: Java SE 7 TreeMap<Integer, String> treeMap = new TreeMap<>(); Java SE 7 TreeMap<Integer, String> treeMap = new TreeMap<Integer, String>(); treeMap.put(10, "ten"); treeMap.put(4, "fou...

First, we create an empty set, and insert some elements into it: Java SE 7 TreeSet<Integer> treeSet = new TreeSet<>(); Java SE 7 TreeSet<Integer> treeSet = new TreeSet<Integer>(); treeSet.add(10); treeSet.add(4); treeSet.add(1); treeSet.add(12); Once we hav...

Since TreeMaps and TreeSets maintain keys/elements according to their natural ordering. Therefor TreeMap keys and TreeSet elements have to comparable to one another. Say we have a custom Person class: public class Person { private int id; private String firstName, lastName; priva...

TreeMap and TreeSet are not thread-safe collections, so care must be taken to ensure when used in multi-threaded programs. Both TreeMap and TreeSet are safe when read, even concurrently, by multiple threads. So if they have been created and populated by a single thread (say, at the start of the pro...