Background

A few days ago I needed to examine the contents of a string collection.

I was surprised that the contents of the collection were not dumped.

What was dumped instead is the collections’ class name.

Examination

Outline

Let us give a couple of use cases:-

1. Array of String
2. System.Collections.Generic.List<string>
3. System.Collections.Specialized.StringCollection
4. System.Collections.Specialized.StringCollection Convert

 

Array of String

Outline

1. Declare Array of String
   • string[] arrayString = new string[2]
2. To concatenate all the strings, we can issue string.join

Code

private static String prepareFilelistUsingArrayofString()
	{
		
		String strListofFileNames = "";
		string[] arrayString = new string[2];
        		
		arrayString[0] = "file -01";
		arrayString[1] = "file -02";
		
		strListofFileNames = string.Join
                   (
                       System.Environment.NewLine + CHAR_TAB
                     , arrayString
                   );

		return (strListofFileNames);
		
	}

Output

Output Image

System.Collections.Generic.List<string>

Outline

1. Declare Collections.Generic.List<string>
   • System.Collections.Generic.List<string> objListofFiles
2. Initialize Variable
   • objListofFiles = new System.Collections.Generic.List<string>();
3. To concatenate all the strings, we can issue string.join

Code

	private static String prepareFilelistUsingListString()
	{

                System.Collections.Generic.List<string> objListofFiles;
		
		objListofFiles = new System.Collections.Generic.List<string>();
		
		String strListofFileNames="";
		

		objListofFiles.Add("file -01");
		objListofFiles.Add("file -02");
		
		strListofFileNames 
                      = string.Join
                        (
                           System.Environment.NewLine + CHAR_TAB 
                         , objListofFiles
                       );

		return (strListofFileNames);
		
	}

Output

Output Image

System.Collections.Generic.List<string>

Outline

1. Declare System.Collections.Specialized.StringCollection
   • System.Collections.Specialized.StringCollection objListofFiles
2. Initialize Variable
   • objListofFiles = new System.Collections.Specialized.StringCollection();
3. To concatenate all the strings, issuing string.join returns the class’s name

Code

private static String prepareFilelistUsingStringCollection()
	{
		
		String strListofFileNames = "";
		
		System.Collections.Specialized.StringCollection objListofFiles = null;
		
                objListofFiles = new System.Collections.Specialized.StringCollection();
        		
		objListofFiles.Add("file -01");
		objListofFiles.Add("file -02");
		
		strListofFileNames 
			= string.Join
                          (
				System.Environment.NewLine 
				    + CHAR_TAB 
                              , objListofFiles
                         );

		return (strListofFileNames);
		
	}

Output

Output Image

 

Explanation

The list’s contents are not displayed.

What is displayed is the object’s name.

 

System.Collections.Generic.List<string>

Outline

1. Declare System.Collections.Specialized.StringCollection
   • System.Collections.Specialized.StringCollection objListofFiles
2. Initialize Variable
   • objListofFiles = new System.Collections.Specialized.StringCollection();
3. To concatenate all the strings, we issued string.join
4. We have to convert the StringCollection
   • StringArray
     • Declare String Array
       • string[] strArray;
     • Allocate String Array based on the size of the StringCollection
       • strArray = new string[objListofFiles.Count];
     • Copy stringCollection to initialized Array
       • objListofFiles.CopyTo(strArray,0);
   •  Use System.Linq namespace, Enumerable.Cast<TResult>
     • Import System.Linq
       • using System.Linq;
     • Declare System.Collections.Generic.List
       • System.Collections.Generic.List<string> listString;
     • Cast StringCollection to StringCollection and then get convert the result to List
       • listString = objListofFiles.Cast<String>().ToList();

Code

	enum enumConversionChoice
	{
    	          convertToStringArray
		, convertToIEnumerable	
	};

	private static String prepareFilelistUsingStringCollectionConverted
	(
		enumConversionChoice choice
	)
	{
		
		String strListofFileNames = "";
		
		System.Collections.Specialized.StringCollection objListofFiles
				= new  System.Collections.Specialized.StringCollection();
		
		
		objListofFiles.Add("file -01");
		objListofFiles.Add("file -02");
		
		if (choice == enumConversionChoice.convertToStringArray)
		{
			
        	         string[] strArray;
		
			strArray = new string[objListofFiles.Count];
		
			objListofFiles.CopyTo(strArray,0);
		
			strListofFileNames 
				= string.Join
                                  (
					  System.Environment.NewLine + CHAR_TAB 
					, strArray
				  );

		}	
		else if (choice == enumConversionChoice.convertToIEnumerable)
		{
			
        	        System.Collections.Generic.List<string> listString = null;
 
                        listString = objListofFiles.Cast<String>().ToList();
		
			strListofFileNames
				= string.Join
				  (
					   System.Environment.NewLine + CHAR_TAB 
					 , listString
				  );

		}	
			
		return (strListofFileNames);
		
	}
	

 

Source Code

GitHub

DanielAdeniji/stringCollectionDump.cs
Link

Summary

There are quite a few ways to store strings.

Strings arrays have some limitations.

Unfortunately, the System.Collections.Specialized.StringCollection class does not have a method to directly dump an object’s instance.

References

1. vurdalakov
   • [C#] How to convert StringCollection to List<String> or other IEnumerable<String> typeLink