SortedMap subMap() method in Java
Last Updated :
26 Nov, 2018
The subMap() method of
SortedMap interface in Java is used to return a view of the portion of this map whose keys range from
fromKey, inclusive, to
toKey, exclusive.
- The map returned by this method is backed by this map, so changes in the returned map are reflected in this map, and vice-versa.
- The map returned by this method supports all optional map operations that this map supports.
Note: The map returned by this method will throw an IllegalArgumentException if an attempt is made to insert a key outside its range.
Syntax:
SortedMap<K, V> subMap(K fromKey,
K toKey)
Where, K is the type of key maintained by this Set and V is the type of values associated with the Key.
Parameters: This function accepts two parameter
fromKey and
toKey which represents low endpoint (inclusive) and high endpoint (exclusive) respectively of the keys in the returned map.
Return Value: It returns a view of the portion of this map whose keys range from
fromKey to
toKey.
Exception:
- ClassCastException: If the parameter fromKey is not compatible with this map's comparator (or, if the map has no comparator, if fromKey does not implement Comparable).
- NullPointerException: If the parameter fromKey is null and this map does not permit null keys.
- IllegalArgumentException: If this map itself has a restricted range, and fromKey lies outside the bounds of the range
Below programs illustrate the above method:
Program 1:
Java
// A Java program to demonstrate
// working of SortedSet
import java.util.*;
public class Main {
public static void main(String[] args)
{
// Create a TreeSet and inserting elements
SortedMap<Integer, String> mp = new TreeMap<>();
// Adding Element to SortedSet
mp.put(1, "One");
mp.put(2, "Two");
mp.put(3, "Three");
mp.put(4, "Four");
mp.put(5, "Five");
// Returning the key ranging
// between 2 and 5
System.out.print("Elements in range from 2 to 5 in the map is : "
+ mp.subMap(2, 5));
}
}
Output:
Elements in range from 2 to 5 in the map is : {2=Two, 3=Three, 4=Four}
Program 2:
Java
// A Java program to demonstrate
// working of SortedSet
import java.util.*;
public class Main {
public static void main(String[] args)
{
// Create a TreeSet and inserting elements
SortedMap<String, String> mp = new TreeMap<>();
// Adding Element to SortedSet
mp.put("One", "Geeks");
mp.put("Two", "For");
mp.put("Three", "Geeks");
mp.put("Four", "Code");
mp.put("Five", "It");
// Returning the key range between D and Z
System.out.print("Key in range from D to Z in the map is : "
+ mp.subMap("D", "Z"));
}
}
Output:
Key in range from D to Z in the map is : {Five=It, Four=Code, One=Geeks, Three=Geeks, Two=For}
Reference:
https://docs.oracle.com/javase/10/docs/api/java/util/SortedMap.html#subMap(K)