ResourceReader Class

The first method of enumerating the resources in a .resources file involves directly retrieving each resource's name/value pair. After you call the IDictionaryEnumerator.MoveNext method to move to each resource in the collection, you can retrieve the resource name from the IDictionaryEnumerator.Key property and the resource data from the IDictionaryEnumerator.Value property.

The following example shows how to retrieve the name and value of each resource in a .resources file by using the IDictionaryEnumerator.Key and IDictionaryEnumerator.Value properties. To run the example, create the following text file named ApplicationResources.txt to define string resources.

Title="Contact Information"Label1="First Name:"Label2="Middle Name:"Label3="Last Name:"Label4="SSN:"Label5="Street Address:"Label6="City:"Label7="State:"Label8="Zip Code:"Label9="Home Phone:"Label10="Business Phone:"Label11="Mobile Phone:"Label12="Other Phone:"Label13="Fax:"Label14="Email Address:"Label15="Alternate Email Address:"

You can then convert the text resource file to a binary file named ApplicationResources.resources by using the following command:

resgen ApplicationResources.txt

The following example then uses the ResourceReader class to enumerate each resource in the standalone binary .resources file and to display its key name and corresponding value.

using System;
using System.Collections;
using System.Resources;

public class Example
{
   public static void Main()
   {
      Console.WriteLine("Resources in ApplicationResources.resources:");
      ResourceReader res = new ResourceReader(@".\ApplicationResources.resources");
      IDictionaryEnumerator dict = res.GetEnumerator();
      while (dict.MoveNext())
         Console.WriteLine("   {0}: '{1}' (Type {2})", 
                           dict.Key, dict.Value, dict.Value.GetType().Name);
      res.Close();
   }
}
// The example displays the following output:
//       Resources in ApplicationResources.resources:
//          Label3: '"Last Name:"' (Type String)
//          Label2: '"Middle Name:"' (Type String)
//          Label1: '"First Name:"' (Type String)
//          Label7: '"State:"' (Type String)
//          Label6: '"City:"' (Type String)
//          Label5: '"Street Address:"' (Type String)
//          Label4: '"SSN:"' (Type String)
//          Label9: '"Home Phone:"' (Type String)
//          Label8: '"Zip Code:"' (Type String)
//          Title: '"Contact Information"' (Type String)
//          Label12: '"Other Phone:"' (Type String)
//          Label13: '"Fax:"' (Type String)
//          Label10: '"Business Phone:"' (Type String)
//          Label11: '"Mobile Phone:"' (Type String)
//          Label14: '"Email Address:"' (Type String)
//          Label15: '"Alternate Email Address:"' (Type String)

The attempt to retrieve resource data from the IDictionaryEnumerator.Value property can throw the following exceptions:

• A FormatException if the data is not in the expected format.

• A FileNotFoundException if the assembly that contains the type to which the data belongs cannot be found.

• A TypeLoadException if the type to which the data belongs cannot be cannot be found.

Typically, these exceptions are thrown if the .resources file has been modified manually, if the assembly in which a type is defined has either not been included with an application or has been inadvertently deleted, or if the assembly is an older version that predates a type. If one of these exceptions is thrown, you can retrieve resources by enumerating each resource and calling the GetResourceData method, as the following section shows. This approach provides you with some information about the data type that the IDictionaryEnumerator.Value property attempted to return.

The second approach to enumerating resources in a .resources file also involves navigating through the resources in the file by calling the IDictionaryEnumerator.MoveNext method. For each resource, you retrieve the resource's name from the IDictionaryEnumerator.Key property, which is then passed to the GetResourceData method to retrieve the resource's data. This is returned as a byte array in the resourceData argument.

This approach is more awkward than retrieving the resource name and value from the IDictionaryEnumerator.Key and IDictionaryEnumerator.Value properties, because it returns the actual bytes that form the resource value. However, if the attempt to retrieve the resource throws an exception, the GetResourceData method can help identify the source of the exception by supplying information about the resource's data type. For more information about the string that indicates the resource's data type, see GetResourceData.

The following example illustrates how to use this approach to retrieve resources and to handle any exceptions that are thrown. It programmatically creates a binary .resources file that contains four strings, one Boolean, one integer, one bitmap, and one custom DateTimeTZI object. To run the example, do the following:

1. Create an assembly named Library.dll that contains the DateTimeTZI structure. The following is the source code for the assembly.

   Compile the source code in C# by using the following command:

   Copy

   csc /t:library library.cs
   

   Or, you can compile it in Visual Basic by using the following command:

   Copy

   vbc library.vb /t:library
   

2. Compile and execute the following source code, which creates a .resources file named ContactResources.resources.

   The source code file is named CreateResources.cs. You can compile it in C# by using the following command:

   Copy

   csc CreateResources.cs /r:library.dll
   

   Or, you can compile it in Visual Basic by using the following command:

   Copy

   vbc CreateResources.vb /r:library.dll
   

3. Compile and run the following code to enumerate the resources in the ContactResources.resources file.

   After modifying the source code (for example, by deliberately throwing a FormatException at the end of the try block) or renaming the Library.dll assembly so that it is unavailable at runtime, you can run the example to see how calls to GetResourceData enable you to retrieve or recreate some resource information.