C# How to add an element to List<string>?

Question

How to add an element movie, to an existing category element? Currently im just able, to create new list entries on both fields.

class MovieSolver
    {
        public string Category { get; set; }
        public List<string> Movie { get; set; }
    }

class CreateMovieList
    {
        readonly static List<MovieSolver> playerTargetList = new List<MovieSolver>();

        public static void MovieCBO()
        {
            playerTargetList.Add(new MovieSolver { Category = "Action", Movie = new List<string> { "Taken", "The Factory", "Wind River" } });
            playerTargetList.Add(new MovieSolver { Category = "Comedy", Movie = new List<string> { "Gold", "Hangover", "We are the Millers" } });
            playerTargetList.Add(new MovieSolver { Category = "Thriller", Movie = new List<string> { "Jack Reacher", "Real Steel", "Iron Man I" } });
        }
    }

Beside is there a smarter way to create the class MovieSolver?

I assume your title is meant to be List<string>. Where does List<List<int>> come from. And what do you mean by 'smarter'? — Peter Smith
– Peter Smith, Commented May 15, 2020 at 16:32
Just not sure if i have done it the right way, as i have to to loop twice to access the List. — Roberto Pagnotta
– Roberto Pagnotta, Commented May 15, 2020 at 16:39
Three steps 1) Create top level elements : List<List<int>> numbers = new List<List<int>>; 2) Create one dimensions list : List<int> number = new List<int>() { 1,2,3,4,5}; 3) add one dimension list to two dimensional list numbers.Add(number); — jdweng
– jdweng, Commented May 15, 2020 at 16:42

CorSix · Accepted Answer · 2020-05-15 16:47:21Z

1

First of all, i cant find a int list here at all.

If you want to add a new string object to the List in a MoveiSolver object you first need to find the Moviesolver object were you want to add the new string element.

You can do this with a for loop, foreach loop or with LINQ.

foreach is often the most easy to understand for new coders.

Foreach item in playerTargetList
{
 if(item.category == "Action")
 {
  item.Movie.add("lorum ipsum");
 }
}

edited May 15, 2020 at 16:47

answered May 15, 2020 at 16:38

CorSix

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1 Comment

Roberto Pagnotta Over a year ago

Thanks for the nice and proper explanation, its working perfectly :)

Herber230 · Accepted Answer · 2020-05-15 17:14:20Z

0

You could add a method addMovie to class CreateMovieList that verifies if the MovieSolver doesn't exist yet and creates it if necessary

public static void addMovie(String category, String movie) 
{
    var movieSolver = playerTargetList.Find(e => e.Category == category);
    if(movieSolver != null) 
    {
        var existingMovie = movieSolver.Movie.Find( e => e == movie);
        if (existingMovie == null)
            movieSolver.Movie.Add(movie);
    }
    else
        playerTargetList.Add(new MovieSolver  { Category = category, Movie = new List<string> { movie } }); 
}

answered May 15, 2020 at 17:14

Herber230

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1 Comment

Roberto Pagnotta Over a year ago

Exactly this i have done based on the input from @saratcsss. addMovie by using the Dictionary solution. Thanks for support

saratcsss · Accepted Answer · 2020-05-15 17:52:20Z

0

Why don't you use a default class like Dictionary<string, List<string>> here?

//Add library reference
using System.Collections.Generic;

public void MyMethod()
{
    //Initialize a Dictionary
    Dictionary<string, List<string>> MovieCBO = new Dictionary<string, List<string>>();
    //Check if its an existing category
    //If its an existing category, add the movie to existing list
    if (MovieCBO.ContainsKey("some_category"))
    {
        MovieCBO["some_category"].Add("new_movie_name");
    }
    //If its a new category, add category along the movie
    else
    {
        MovieCBO.Add("some_category", new List<string>() { "new_movie_name" });
    }
}

All operations will be done in constant time. It would much faster than iterating through all the items in a list and checking the category.

edited May 15, 2020 at 17:52

answered May 15, 2020 at 16:53

saratcsss

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4 Comments

Roberto Pagnotta Over a year ago

Im currently trying to implement your solution, but i get no output, no error. I think is related to if (MovieCBO.ContainsKey("some_category")) . Should the if statement not be linked to playerTargetList This is actually what im currently trying to make the code work... I can accept just one answer. As soon your code above works im going to give you that tick.

saratcsss Over a year ago

What's the name of the dictionary you declared? if (<your_dictionary>.ContainsKey("key_value")) should be used.

Roberto Pagnotta Over a year ago

i used your declaration Dictionary<string, List<string>> MovieCBO = new Dictionary<string, List<string>>();

Roberto Pagnotta Over a year ago

As i understood the logic, is if a category is existing it will add just the movie, else category and movie... the code its complete on my initial post, there is just a button to run MovieCBO() and MyMethod()

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