assign an ArrayList to a List in java

Question

I am implementing the code that can considering the following junit test:

package it.unica.pr2.pizze.test;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.fail;
import static org.junit.Assert.assertTrue;

import org.junit.Test;
import org.junit.Ignore;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import java.util.*; 
import it.unica.pr2.pizze.*; 

@RunWith(JUnit4.class)
public class TestPizza {

  @Test
    public void test1() {
      Ingrediente mozzarella = new Ingrediente("mozzarella",50);
      Ingrediente pomodoro = new Ingrediente("pomodoro",10);
      Ingrediente[] ingredienti = new Ingrediente[] {mozzarella, pomodoro}
      Pizza pizzaMargherita = new Pizza(ingredienti);
      assertTrue( pizzaMargherita.calorie() == 60 );
      List ingredientiMargherita = pizzaMargherita;
        assertTrue(ingredientiMargherita.size() ==2);
        assertTrue(ingredientiMargherita.get(0) == mozzarella);
        assertTrue(ingredientiMargherita.get(1) == pomodoro);
     }

and here is my classe: Pizza

package it.unica.pr2.pizze;
import java.util.ArrayList;
import java.util.List;

public class Pizza  {


    private ArrayList<Ingrediente> ingredienti;


    public Pizza(Ingrediente[] ing) {

        this.ingredienti = new ArrayList<>();

        int i = 0;
        while (i < ing.length) {

            this.ingredienti.add(ing[i]);
            i++;
        }

    }

    public double calorie(){

        double sumaCalorie = 0;

        for(Ingrediente elem: this.ingredienti)
            sumaCalorie += elem.getCalorie();

        return sumaCalorie;

    }
}

and an other class: Ingrediente

package it.unica.pr2.pizze;


public class Ingrediente  {


    private String nomeIngrediente;
    private double calorie;



    public Ingrediente(String nomeIngrediente, double calorie) throws IngredienteNonValidoException {

        this.nomeIngrediente = nomeIngrediente;
        if (calorie < 0) throw new IngredienteNonValidoException();
        else
            this.calorie = calorie;
    }

    public void setNomeIng(String nomeIngrediente) {
        this.nomeIngrediente = nomeIngrediente;
    }

    public void setCalorie(double calorie) {

        this.calorie = calorie;
    }

    public String getNomeIng() {

        return this.nomeIngrediente;
    }

    public double getCalorie() {
        return this.calorie;
    }

}

After running the test I got the following error:

error: incompatible types: Pizza cannot be converted to List

List ingredientiMargherita = pizzaMargherita;

So I don't know how to convert an ArrayList into a List just using the operator =, I can not modify the junit test code.

I am 99% sure the unit test code has an error in it. If this was an assignment, go back to your professor and ask if they really meant the line "List ingredientiMargherita = pizzaMargherita;" rather than "List ingredientiMargherita = pizzaMargherita.getIngrediente();". Otherwise the only solution is markspace's. — DJClayworth
– DJClayworth, Commented May 28, 2015 at 21:39
Yes, the test code is rather suspect. I would verify that it's not mistaken. Requiring a value class like Pizza to implement List is kinda weird. — markspace
– markspace, Commented May 28, 2015 at 21:42
Either that or what OP has tried to re-write to run the program. — hitz
– hitz, Commented May 28, 2015 at 21:45
no error in the unit test, the solution i found is here below. — rainman
– rainman, Commented May 30, 2015 at 14:04

markspace · Accepted Answer · 2015-05-28 21:35:24Z

3

If you can't modify the assignment, you have to do this:

public class Pizza implements List {
...
}

Or something equivalent, like

public class Pizza extends AbstractList {
...
}

answered May 28, 2015 at 21:35

markspace

11.1k3 gold badges28 silver badges44 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

DJClayworth Over a year ago

From a design point of view this is a terrible solution. But it's the only one that could work. +1.

markspace Over a year ago

Yeah, I know, it's kinda ugly. I think your comment about the test case likely being a typo is probably worth it for the OP to check.

DJClayworth Over a year ago

And no criticism intended, in case you took it that way. Just wanted to make sure that people didn't try doing this where they didn't have to.

hitz · Accepted Answer · 2015-05-28 21:38:53Z

1

On below line in your unit test you are assigning Pizza type to a List:

List ingredientiMargherita = pizzaMargherita;

Change it to something like:

List<Ingrediente> ingredientiMargherita = pizzaMargherita.getIngredienti();

And add a getIngredienti() to return List in your Pizza class:

public ArrayList<Ingrediente> getIngredienti(){
     return ingredienti;
}

answered May 28, 2015 at 21:38

hitz

1,1108 silver badges12 bronze badges

1 Comment

markspace Over a year ago

This also works, but when the OP said he/she couldn't modify the assignment, I assumed a modification to the test code like this was not possible. If it is possible, this is likely the better solution.

rainman · Accepted Answer · 2015-05-29 21:05:05Z

1

i found a solution without editing the junit test code, i had to modify my Pizza.java as follows:

package it.unica.pr2.pizze;
import java.util.ArrayList;
import java.util.*;

public class Pizza extends ArrayList   {

    public Pizza(Ingrediente[] ing) {

        for(Ingrediente elem: ing) {

            this.add(elem);
        }

    }

    public int calorie() {
        int calorie = 0;
        for(Object i : this) {
            calorie += ((Ingrediente)i).getCalorie();
        }
        return calorie;
    }


}

now the test is passed correctly.

answered May 29, 2015 at 21:05

rainman

2,6596 gold badges31 silver badges47 bronze badges

Collectives™ on Stack Overflow

assign an ArrayList to a List in java

3 Answers 3

3 Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related