Click here to watch in Youtube : https://www.youtube.com/watch?v=Rlu2onjotZ0&list=UUhwKlOVR041tngjerWxVccwTreeMapExample.java import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
/*
* Example of headMap(K toKey) method.
*/
public class TreeMapExample
{
public static void main( String[] args )
{
TreeMap<Integer, String> treeMap = new TreeMap<Integer, String>();
treeMap.put(10, "Cat");
treeMap.put(50, "Dog");
treeMap.put(30, "Apple");
treeMap.put(40, "Ball");
treeMap.put(20, "Eagle");
System.out.println("treeMap : " + treeMap + "\n");
/*
* Returns a view of the portion of this map whose keys are strictly
* less than toKey. 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.
*
* Equivalent to headMap(toKey, false).
*/
SortedMap<Integer, String> sortedMap = treeMap.headMap(40);
System.out.println("sortedMap : " + sortedMap + "\n");
Set<Integer> set = sortedMap.keySet();
System.out.println("set : " + set + "\n");
System.out.println("-----------------------");
System.out.println("Key" + " | " + "value");
System.out.println("-----------------------");
for( Integer key : set )
{
String value = sortedMap.get(key);
System.out.println(key + " | " + value);
}
}
}
Output treeMap : {10=Cat, 20=Eagle, 30=Apple, 40=Ball, 50=Dog}
sortedMap : {10=Cat, 20=Eagle, 30=Apple}
set : [10, 20, 30]
-----------------------
Key | value
-----------------------
10 | Cat
20 | Eagle
30 | Apple