CODEWITHSUNDEEP
java
Michael
Michael

Reputation: 13616

How to make class iterable with foreach?

I have this class:

import java.util.Iterator;
import java.util.HashMap;
import java.util.Map;

public class Polynomial<T> implements Iterable<T>  {
    Map<Integer, Object> polynomial;

    public Polynomial(){
        polynomial = new HashMap<Integer, Object>();
    }
    public  Polynomial(int numberOfMembers){
        polynomial = new HashMap<Integer, Object>(numberOfMembers);
    }
    public void addElm(int power, int coefficient){
        if (power < 0) {
            power = Math.abs(power);
            throw new RuntimeException("ERROR: The power must be an absolute number, converting to absolute");
        }
        for (Map.Entry m : polynomial.entrySet()) {
            if ((Integer) m.getKey() == power){
                polynomial.put(power,m.getValue());
            }
        }
    }
    @Override
    public Iterator<T> iterator() {
        // TODO Auto-generated method stub
        return (Iterator<T>) new Object;
    }

}

And here is part of main function:

 Polynomial<Integer> p1=new Polynomial<Integer>();
 for (Integer r : p1)
 System.out.println(r.toString());

As you can see above I need to make foreach on Polynomial class, that's why Polynomial implement Iterable interface. But my problem that I don't know how to implement iterator() method. How can I do that?

Upvotes: 0

Views: 549

Answers (1)

Sweeper
Sweeper

Reputation: 271750

Your code is very confusing. What is T? Why is T not used in the class? What is the coefficient parameter used for? What are you trying to do?

My best guess is that T is the type of coefficient of the polynomial, and you are trying to return an iterator that iterates through the coefficients.

I rewrote your code like this:

public class Polynomial<T> implements Iterable<T>  {
    Map<Integer, T> polynomial;

    public Polynomial(){
        polynomial = new HashMap<Integer, T>();
    }
    public  Polynomial(int numberOfMembers){
        polynomial = new HashMap<Integer, T>(numberOfMembers);
    }
    public void addElm(int power, T coefficient){
        if (power < 0) {
            throw new RuntimeException("ERROR: The power must be an absolute number");
        }
        polynomial.put(power,coefficient);
    }
    @Override
    public Iterator<T> iterator() {
        return polynomial.values().iterator();
    }

}

Upvotes: 3

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