How to convert list of strings to an existing object list?

Question

I am wanting to save / restore object data in my Windows Phone 8 application. The objects are logs, each log having its own properties. The master list of logs is named logArray.

However the case, I do not know how to convert the saved .txt file back into the logArray, for when the app starts back up! Here is my code:

    private async Task WriteToFile()
    {
        try
        {
            if (File.Exists("Logs.txt"))
            {
                File.Delete("Logs.txt");
            }

            StreamWriter write = new StreamWriter("Logs.txt");

            //Write each log element to a new string line
            foreach (Log element in logArray)
            {
                await write.WriteLineAsync();
            }
        }

        catch (Exception e)
        {
            Console.WriteLine("Error: " + e.ToString());
        }

    }

    private async Task ReadFromFile()
    {
        try
        {
            //Variable definitions
            StreamReader read = new StreamReader("Logs.txt");
            List<String> lines = new List<String>();
            String line;


            if (File.Exists("Logs.txt"))
            {
                //Read each string line into a string list
                while ((line = await read.ReadLineAsync()) != null)
                {
                    lines.Add(line);
                }

                foreach (String element in lines)
                {
                    //Convert String line to logArray object

                }
            }  
        }

        catch (Exception e)
        {
            Console.WriteLine("Error: " + e.ToString());
        } 
    }

Answer 1

Perhaps you should consider serializing and de-serializing using a markup anguage like XML or JSON, and then storing your text to a file.

an example for XML serialization using a simple car object:

public static void WriteFile()
{
    Car testCar= new Car();
    string path = "c:\temp\testCarPath.xml";
    XmlSerializer serializer = new XmlSerializer(typeof(Car));
    StreamWriter file = new StreamWriter(path);

    serializer.Serialize(file, testCar);
    file.Close();
}
public static void ReadFile()
{
    Car testCar;
    string path = "c:\temp\testCarPath.xml";
    XmlSerializer serializer = new XmlSerializer(typeof(Car));
    StreamReader reader = new StreamReader(path);

    testCar = (Car)serializer.Deserialize(reader);
    reader.Close();
}

Answer 2

If you are asking how to convert your lines variable which is a List<string> into an array of strings, then that's simply string[] logArray = lines.ToArray();.

But if you are asking about loading and saving an array or List (of strings) to a text file, then the following covers that, which you might want to read to simplify your code a lot.

I don't understand why people mess with a StreamReader and StreamWriter at all when they really simply want to read and write from a text file. Is this what you are asking?

Why not just use File.WriteAllLines("logs.txt", lines); to write it out to the text file?

You can use List<string> lines = File.ReadAllLines("log.txt").ToList(); too, or if you don't need a List then string[] lines = File.ReadAllLines("log.txt"); for one more step of simplicity.

of course you can slice and dice the data however your heart desires once you have every line in an array or List in memory too. these just skip about 20 lines of unnecessary code. ;)

happy coding!!