TreeMap SortedMap tailMap(K fromKey) Method Example Program


Returns a view of the portion of this map whose keys are greater than or equal to fromKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
The returned map will throw an IllegalArgumentException on an attempt to insert a key outside its range.

Equivalent to tailMap(fromKey, true).

Program

package com.candidjava;

import java.util.TreeMap;
import java.util.SortedMap;

/**
 * @author: Hari Haran
 * @discription: The tailMap(K fromKey) method is used to return a view of the
 *               portion of this map whose keys are greater than or equal to
 *               fromKey. The returned map is backed by this map, so changes in
 *               the returned map are reflected in this map, and vice-versa.
 */

public class TreeMapTailMap {
	public static void main(String[] args) {
		TreeMap<Integer, String> tm = new TreeMap<Integer, String>();
		SortedMap<Integer, String> tmin = new TreeMap<Integer, String>();

		tm.put(1, "Anand");
		tm.put(2, "Hari Haran");
		tm.put(8, "Kamal");
		tm.put(4, "Karthikeyan");
		tm.put(5, "Mohan");
		tm.put(6, "Vinoth");
		tm.put(7, "Hari Haran");

		System.out.println("Getting tail map");
		tmin = tm.tailMap(3);
		System.out.println("Tail map values: " + tmin);
	}
}

Output

Getting tail map
Tail map values: {4=Karthikeyan, 5=Mohan, 6=Vinoth, 7=Hari Haran, 8=Kamal}

Explanation

public SortedMap<K,V> tailMap(K fromKey)
Returns a view of the portion of this map whose keys are greater than or equal to fromKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
The returned map will throw an IllegalArgumentException on an attempt to insert a key outside its range.

Equivalent to tailMap(fromKey, true).

Specified by:
tailMap in interface NavigableMap<K,V>
Specified by:
tailMap in interface SortedMap<K,V>
Parameters:
fromKey - low endpoint (inclusive) of the keys in the returned map
Returns:
a view of the portion of this map whose keys are greater than or equal to fromKey
Throws:
ClassCastException - if fromKey is not compatible with this map's comparator (or, if the map has no comparator, if fromKey does not implement Comparable). Implementations may, but are not required to, throw this exception if fromKey cannot be compared to keys currently in the map.
NullPointerException - if fromKey is null and this map uses natural ordering, or its comparator does not permit null keys
IllegalArgumentException - if this map itself has a restricted range, and fromKey lies outside the bounds of the range


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