Chapter 11, Problem 19E

Explanation of Solution

Method “rarest()” to return the integer value that occurs fewer times in the map:

//Import required packages

import java.util.HashMap;

import java.util.Map;

import java.util.TreeMap;

//Definition of class Test

public class Test

{

    //Definition of main class

    public static void main(String[] args)

    {

        //Create a map

Map<String, Integer> valueMap = new HashMap<>();

        // Adding key-value pairs to a HashMap

        valueMap.put("Jack", 56);

        valueMap.put("Lilo", 45);

        valueMap.put("Sherlin", 25);

        valueMap.put("Liya", 75);

        valueMap.put("Leson", 45);

        valueMap.put("Zen", 17);

        valueMap.put("Benith", 25);

        //Call the method "valueMap"

        System.out.println( rarest(valueMap));

    }

    //Definition of method rarest

    public static int rarest(Map<String, Integer> mVal)

    {

        //Check whether the map is empty

        if (mVal == null || mVal.isEmpty())

        {

            //Throw the exception error

            throw new IllegalArgumentException();

        }

    //Create an object for counts

    Map<Integer, Integer> counts = new TreeMap<Integer, Integer>();

    //Traverse the map set

    for (String name : mVal.keySet())

    {

        //Assign the age value

        int age = mVal.get(name);

        //Check the condition for key

        if (counts.containsKey(age))

        {

            //Assign the minimum age

            counts...