Check out example codes for "TreeMap headMap() method in java". It will help you in understanding the concepts better.

Code Example 1

import java.util.SortedMap;
import java.util.TreeMap;
public class TreeMapHeadMapMethodExample
{
   public static void main(String[] args)
   {
      TreeMap<Integer, String> tm = new TreeMap<Integer, String>();
      // map string values to integer keys
      tm.put(65, "mango");
      tm.put(63, "apple");
      tm.put(35, "grapes");
      tm.put(60, "pineapple");
      tm.put(26, "banana");
      System.out.println("Given TreeMap is: " + tm);
      // create SortedMap for map head
      SortedMap<Integer, String> sm = new TreeMap<Integer, String>();
      sm = tm.headMap(60);
      // Getting map head
      System.out.println("headmap is: " + sm);
   }
}

Code Example 2

import java.util.NavigableMap;
import java.util.TreeMap;
public class TreeMapHeadMapBooleanInclusiveMethod
{
   public static void main(String[] args)
   {
      TreeMap<Integer, String> tm = new TreeMap<Integer, String>();
      NavigableMap<Integer, String> nm = new TreeMap<Integer, String>();
      tm.put(96, "violet");
      tm.put(93, "green");
      tm.put(20, "yellow");
      tm.put(36, "red");
      tm.put(53, "blue");
      // get head map inclusive 93
      nm = tm.headMap(93, true);
      System.out.println("Check values of TreeMap");
      System.out.println("Value is: " + nm);
   }
}

Code Example 3

import java.util.SortedMap;
import java.util.TreeMap;
public class TreeMapHeadMapMethodExample
{
   public static void main(String[] args)
   {
      TreeMap<String, Integer> tm = new TreeMap<String, Integer>();
      // map string values to integer keys
      tm.put("mango", 65);
      tm.put("apple", 63);
      tm.put("grapes", 35);
      tm.put("pineapple", 60);
      tm.put("banana", 26);
      System.out.println("Given TreeMap is: " + tm);
      // create SortedMap for map head
      SortedMap<String, Integer> sm = new TreeMap<String, Integer>();
      sm = tm.headMap("pineapple");
      // Getting map head
      System.out.println("headmap is: " + sm);
   }
}

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