如何将 ToString() 方法覆盖到 output 列表？

Question

Is it possible to override the ToString() method to output a list? Here's my code

    namespace CircularClass
{
    class InfinitelyCircular
    {

        public class RatsInAShip
        {
            public string RatBreed;
            public string RatWeight;
            public string RatAge;
            public bool HasChildren;
            public List<RatsInAShip> RatChildren;
            public override string ToString()
            {
                return String.Format("RatBreed:{0}\n RatWeight:{1}\n RatAge:{2}\n HasChildren:{3}",RatBreed, RatWeight, RatAge, HasChildren);
            }
        }

        static void Main(string[] args)
        {
            var mu = new RatsInAShip()
                         {
                             RatAge = "100",
                             RatBreed = "RexRat",
                             RatWeight = "200",
                             HasChildren = true,
                             RatChildren = new List<RatsInAShip>()
                         };

            for (var i = 0; i < 3; i++)
            {
                var cu = new RatsInAShip()
                             {
                                 RatAge = "100",
                                 RatBreed = "DwarfRat"+i,
                                 RatWeight = "200",
                                 HasChildren = false
                             };
                mu.RatChildren.Add(cu);
            }

            //Output
                Console.WriteLine(String.Format("{0}, {1}", mu.RatBreed, mu.RatChildren[0]));

        }
    }
}

How can I override ToString() to output all the children in a list?

Answer 1

Looks like you're already overriding the ToString() method on your class... so... use a StringBuilder and a for/foreach loop to construct your output string?

Answer 2

Perhaps you would could output the children in a foreach loop, like this:

public override string ToString()
{
    StringBuilder sb = new StringBuilder();
    sb.AppendFormat("RatBreed:{0}\n RatWeight:{1}\n RatAge:{2}\n HasChildren:{3}\n",RatBreed, RatWeight, RatAge, HasChildren);
    foreach (RatsInAShip rat in RatChildren)
    {
        sb.AppendFormat("\tRat Child: {0}\n", rat);
    }
    return sb.ToString();
}

I haven't compiled this, so please correct me if I made a mistake. [edit] compiled now... :)

Answer 3

To output a list? As in, return a list? No. Two reasons:

1. You can't change the return type of an overridden method.
2. ToString() implies that it returns a string. Returning anything else would be highly unintuitive and invites support problems with the code.

Answer 4

You can't change the return type of an overriden method.

You will need to write your own method that returns a list:

public IList<string> ToList()
{
  // your code that returns a list of strings
}

Answer 5

Yes:

public override string ToString()
{
    string result = "";
    if(RatChildren != null)
      foreach(var x in RatChildren)
        result += String.Format("RatBreed:{0}\n RatWeight:{1}\n RatAge:{2}\n HasChildren:{3}", x.RatBreed, x.RatWeight, x.RatAge, x.HasChildren);

    return result;
}

Answer 6

You can override the ToString as you have done already. You could iterate through the elements of the list to output the string of your desire.