ConcurrentSkipListMap in Java with Examples

// Java Program to Demonstrate
// ConcurrentSkipListMap

import java.io.*;
import java.util.*;
import java.util.concurrent.*;

class ConcurrentSkipListMapExample {
    public static void main(String[] args)
    {
        // create an instance of ConcurrentSkipListMap
        ConcurrentSkipListMap<String, String> cslm
            = new ConcurrentSkipListMap<String, String>();

        // Add mappings using put method
        cslm.put("3", "Geeks");
        cslm.put("2", "from");
        cslm.put("1", "Hi!");
        cslm.put("5", "Geeks");
        cslm.put("4", "for");

        // print to the console
        System.out.println("Initial Map : " + cslm);

        // print key-value pair whose key is greater than 2
        System.out.println("ceilingEntry-2: "
                           + cslm.ceilingEntry("2"));

        // get the descending key set
        NavigableSet navigableSet = cslm.descendingKeySet();

        System.out.println("descendingKeySet: ");

        // Iterate through the keySet
        Iterator itr = navigableSet.iterator();
        while (itr.hasNext()) {
            String s = (String)itr.next();
            System.out.println(s);
        }

        // print the first mapping
        System.out.println("firstEntry: "
                           + cslm.firstEntry());

        // print the last mapping
        System.out.println("lastEntry: "
                           + cslm.lastEntry());

        // remove the first mapping and print it
        System.out.println("pollFirstEntry: "
                           + cslm.pollFirstEntry());

        // print the first mapping
        System.out.println("now firstEntry: "
                           + cslm.firstEntry());

        // remove the last mapping and print it
        System.out.println("pollLastEntry: "
                           + cslm.pollLastEntry());

        // print the last mapping
        System.out.println("now lastEntry: "
                           + cslm.lastEntry());
    }
}

// Java Program to demonstrate adding
// mappings to a ConcurrentSkipListMap

import java.util.concurrent.*;

class AddingMappingsExample {
    public static void main(String[] args)
    {

        // Initializing the map
        ConcurrentSkipListMap<Integer, Integer> cslm
            = new ConcurrentSkipListMap<Integer, Integer>();

        // Adding elements to this map
        for (int i = 1; i <= 9; i++)
            cslm.put(i, i);

        // put() operation on the map
        System.out.println("After put(): " + cslm);
    }
}

// Java Program Demonstrate removing
// mappings from ConcurrentSkipListMap

import java.util.concurrent.*;

class RemovingMappingsExample {
    public static void main(String[] args)
    {

        // Initializing the map
        ConcurrentSkipListMap<Integer, Integer> cslm
            = new ConcurrentSkipListMap<Integer, Integer>();

        // Adding elements to this map
        for (int i = 1; i <= 6; i++)
            cslm.put(i, i);

        // remove() operation on the map
        cslm.remove(5);

        // print the modified map
        System.out.println("After remove(): " + cslm);

        // remove the first mapping and print it
        System.out.println("pollFirstEntry: "
                           + cslm.pollFirstEntry());

        // remove the last mapping and print it
        System.out.println("pollLastEntry: "
                           + cslm.pollLastEntry());
          
          // Print final map
          System.out.println("map contents: " + cslm);
    }
}

// Java Program to demonstrate iterating
// over ConcurrentSkipListMap

import java.util.concurrent.*;
import java.util.*;

class IteratingExample {
    public static void main(String[] args)
    {
        // create an instance of ConcurrentSkipListMap
        ConcurrentSkipListMap<Integer, Integer> cslm
            = new ConcurrentSkipListMap<>();

        // Add mappings using put method
        for (int i = 0; i < 6; i++) {
            cslm.put(i, i);
        }

        // Create an Iterator over the
        // ConcurrentSkipListMap
        Iterator<ConcurrentSkipListMap
                     .Entry<Integer, Integer> > itr
            = cslm.entrySet().iterator();

        // The hasNext() method is used to check if there is
        // a next element The next() method is used to
        // retrieve the next element
        while (itr.hasNext()) {
            ConcurrentSkipListMap
                .Entry<Integer, Integer> entry
                = itr.next();
            System.out.println("Key = " + entry.getKey()
                               + ", Value = "
                               + entry.getValue());
        }
    }
}