Java Generics

Mymain.java

import java.util.*;

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

        HashMap<Integer, Double> hashMapData = new HashMap<Integer, Double>();
        hashMapData.put(0, 1.0);
        hashMapData.put(1, 10.0);
        hashMapData.put(2, 4.0);
        hashMapData.put(3, 5.0);

        MyMathClass<Integer, Double> mymathclass = new MyMathClass<Integer, Double>();

        double result = mymathclass.Average(hashMapData);
        System.out.println(result);


        ArrayList resultarr = mymathclass.ConvertTo(hashMapData);
        System.out.println(resultarr.toString());

    }
}

MyMathClass.java

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.lang.Number;

public class MyMathClass<T, V extends Number> {

	public double Average (HashMap<T, V> hashmp){
		double count = 0;
		double sum = 0;
		Iterator <T> i = hashmp.keySet().iterator();

		while (i.hasNext()) {
			int y = (int) i.next();
			sum = (sum + hashmp.get(y).doubleValue());
			count++;
		  }
		  double avg = sum / count;

		return avg;
	}

    public ArrayList<V> ConvertTo(HashMap<T, V> hashmp)
	{
		ArrayList<V> mapValues = new ArrayList<V>(hashmp.values());
		ArrayList<V> exportValues = new ArrayList<V>();
		for (V temp : mapValues) {
			exportValues.add(temp);
		}
		return exportValues;
	}
}

Question.md

Question

This question is based on the Collection Framework and Generics.

• You should implement a generic class, call MyMathClass , with a type and value parameter T, V where V is a numeric object type (e.g., Integer, Double, or any class that extends java.lang.Number )

• Implement a method named Average that takes a HashMapt of type T, V and calculate the average of the HashMap values and display. Hint: use doubleValue () method in the Number class to retrieve the value of each number as a double.

• Implement another method call ConvertTo which convert and store HashMap values to an ArrayList. Method should takes a HashMapt of type T, V and return the ArrayList.

• Implement a class call Mymain which having the main method and test Average and ConvertTo methods with suitable data. Your program should generate a compile-time error if your Average is invoked on a HashMap that is defined for nonnumeric elements as value parameter (e.g., <Strings, String>).