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SortedMap (interface) example in java Collection Framework


In this example I will show you how you can use SortedMap interface in your Java application.

A SortedMap is a map that maintains its entries in ascending order, sorted according to the keys' natural order, or according to a Comparator provided at SortedMap creation time. (Natural order and Comparators are discussed in the section on Object Ordering In addition to the normal Map operations, the Map interface provides operations for:

  • Range-view: Performs arbitrary range operations on the sorted map.
  • Endpoints: Returns the first or last key in the sorted map.
  • Comparator access: Returns the Comparator used to sort the map (if any).

Here is the code of program :

import java.util.*;

public class SortedMapExample{

  public static void main(String[] args) {

    SortedMap map = new TreeMap();

    // Add some elements:

    // Display the lowest key:
    System.out.println("The lowest key value is: " + map.firstKey());

    // Display the highest key:
    System.out.println("The highest key value is: " + map.lastKey());

    // Display All key value
    System.out.println("All key value is:\n" + map);

    // Display the headMap:
    System.out.println("The head map is:\n" + map.headMap("4"));

    // Display the tailMap:
    System.out.println("The tail map is:\n" + map.tailMap("4"));

    // keySet method returns a Set view of the keys contained in this map.
    Iterator iterator = map.keySet().iterator();
    while (iterator.hasNext()) {
      Object key = iterator.next();
      System.out.println("key : " + key + " value :" + map.get(key));


The highest key value is: 5

All key value is:

{1=One, 2=Two, 3=Three, 4=Four, 5=Five}

The head map is:

{1=One, 2=Two, 3=Three}

The tail map is:

{4=Four, 5=Five}

key : 1 value :One

key : 2 value :Two

key : 3 value :Three

key : 4 value :Four

key : 5 value :Five

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