Mega Code Archive

 
Categories / Java Book / 005 Collection
 

0315 SortedMap

Sorted Map is a map that maintains its entries in ascending order., Sorted Map sorts the entries according to the keys' natural ordering or according to a comparator that is supplied when the sorted map is created. Sorted maps are described by the SortedMap interface. TreeMap is an example of a sorted map. SortedMap, whose generic type is SortedMap<K,V>, extends Map. import java.util.Comparator; import java.util.SortedMap; import java.util.TreeMap; public class Main { public static void main(String[] args) { SortedMap<String, Integer> sortedMap = new TreeMap<String, Integer>(); String[] officeSupplies = { "a", "b", "c", "d", "e" }; int[] quantities = { 20, 30, 5, 10, 20 }; for (int i = 0; i < officeSupplies.length; i++){ sortedMap.put(officeSupplies[i], quantities[i]); } System.out.println(sortedMap); System.out.println(sortedMap.headMap("c")); System.out.println(sortedMap.headMap("c")); SortedMap<String, Integer> smsiCopy; Comparator<String> cmp; cmp = new Comparator<String>() { public int compare(String key1, String key2) { return key2.compareTo(key1); // descending order } }; smsiCopy = new TreeMap<String, Integer>(cmp); smsiCopy.putAll(sortedMap); System.out.println(smsiCopy); } } {a=20, b=30, c=5, d=10, e=20} {a=20, b=30} {a=20, b=30} {e=20, d=10, c=5, b=30, a=20}