C# | Type.GetField() Method

Type.GetField() Method is used to get a specific field of the current Type. There are 2 methods in the overload list of this method as follows:

• GetField(String) Method
• GetField(String, BindingFlags) Method

GetField(String) Method

This method is used to search for the public field with the specified name.

Syntax: public System.Reflection.FieldInfo GetField (string name);
Here, it takes the string containing the name of the data field to get.

Return Value: This method returns an object representing the public field with the specified name if found otherwise, null.

Exception: This method throws ArgumentNullException if the name is null .

Below programs illustrate the use of Type.GetField() Method:

Example 1:

// C# program to demonstrate the
// Type.GetField(String) Method
using System;
using System.Globalization;
using System.Reflection;

class GFG {

    // Main Method
    public static void Main()
    {
        // Declaring and initializing object of Type
        Type objType = typeof(Student);

        // try-catch block for handling Exception
        try {

            // Getting FieldInfo by
            // using GetField(String) Method
            FieldInfo info = objType.GetField("Name");

            // Display the Result
            Console.WriteLine("FieldInfo is: {0}", info);
        }

        // catch ArgumentNullException here
        catch (ArgumentNullException e)
        {
            Console.Write("name is null.");
            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }
}

// Defining class Student
public class Student
{
    public string Name = "Rahul";
    public string Dept = "Electrical";
    public int Roll = 10;
}

Output:

FieldInfo is: System.String Name

Example 2: For ArgumentNullException

// C# program to demonstrate the
// Type.GetField(String) Method
using System;
using System.Globalization;
using System.Reflection;

class GFG {

    // Main Method
    public static void Main()
    {
        // Declaring and initializing object of Type
        Type objType = typeof(Student);

        // try-catch block for handling Exception
        try {

            // Getting FieldInfo by
            // using GetField() Method
            FieldInfo info = objType.GetField(null);

            // Display the Result
            Console.WriteLine("FieldInfo is: {0}", info);
        }

        // catch ArgumentNullException here
        catch (ArgumentNullException e)
        {
            Console.WriteLine("Name is null.");
            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }
}

// Defining class Student
public class Student
{
    public string Name = "Rahul";
    public string Dept = "Electrical";
    public int Roll = 10;
}

Output:

name is null.
Exception Thrown: System.ArgumentNullException

GetField(String, BindingFlags) Method

This method is used to search for the specified field, using the specified binding constraints.

Syntax: public abstract System.Reflection.FieldInfo GetField (string name, System.Reflection.BindingFlags bindingAttr);

Parameters:

name: The string containing the name of the data field to get.
bindingAttr: It is a bitmask comprised of one or more BindingFlags that specify how the search is conducted or Zero, to return null.

Return Value: This method returns an object representing the field that matches the specified requirements if found otherwise, null.

Exception: This method throws ArgumentNullException if name is null.

Below programs illustrate the use of the above-discussed method:

Example 1:

// C# program to demonstrate the
// Type.GetField(String) Method
using System;
using System.Globalization;
using System.Reflection;

class GFG {

    // Main Method
    public static void Main()
    {
        // Declaring and initializing object of Type
        Type objType = typeof(Student);

        // try-catch block for handling Exception
        try {

            // You must specify either BindingFlags.Instance
            // or BindingFlags.Static
            // and Specify BindingFlags.Public
            // to include public fields in the search
            BindingFlags battr = BindingFlags.Public | BindingFlags.Instance;

            // Getting FieldInfo by
            // using GetField() Method
            FieldInfo info = objType.GetField("Name", battr);

            // Display the Result
            Console.WriteLine("FieldInfo is: {0}", info);
        }

        // catch ArgumentNullException here
        catch (ArgumentNullException e)
       {
            Console.Write("name is null.");
            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }
}

// Defining class Student
public class Student
{
    public string Name = "Rahul";
    public string Dept = "Electrical";
    public int Roll = 10;
}

Output:

FieldInfo is: System.String Name

Example 2: For ArgumentNullException

// C# program to demonstrate the
// Type.GetField(String) Method
using System;
using System.Globalization;
using System.Reflection;

class GFG {

    // Main Method
    public static void Main()
    {
        // Declaring and initializing object of Type
        Type objType = typeof(Student);

        // try-catch block for handling Exception
        try {

            // You must specify either BindingFlags.Instance
            // or BindingFlags.Static
            // and Specify BindingFlags.Public
            // to include public fields in the search
            BindingFlags battr = BindingFlags.Public | BindingFlags.Instance;

            // Getting FieldInfo by
            // using GetField() Method
            FieldInfo info = objType.GetField(null, battr);

            // Display the Result
            Console.WriteLine("FieldInfo is: {0}", info);
        }

        // catch ArgumentNullException here
        catch (ArgumentNullException e)
        {
            Console.WriteLine("name is null.");
            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }
}

// Defining class Student
public class Student
{
    public string Name = "Rahul";
    public string Dept = "Electrical";
    public int Roll = 10;
}

Output:

name is null.
Exception Thrown: System.ArgumentNullException

Reference:

• https://docs.microsoft.com/en-us/dotnet/api/system.type.getfield?view=netframework-4.8