C# |类型。GetFields()方法
原文:https://www . geesforgeks . org/c-sharp-type-getfields-method/
类型。GetFields()方法用于获取当前类型的字段。此方法的重载列表中有 2 种方法，如下所示:
-
GetFields()方法 *GetFields(BindingFlags) Method
GetFields()方法
此方法用于返回当前类型的所有公共字段。
语法:公共系统。反射. FieldInfo[]GetFields()；
返回值:该方法返回一个表示为当前类型定义的所有公共字段的字段信息对象的数组。或者，如果没有为当前类型定义公共字段，则为字段信息类型的空数组。
以下程序说明了类型的使用。GetFields() 方法:
例 1:
```cs // C# program to demonstrate the // Type.GetFields() 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 array of Fields by // using GetField() Method FieldInfo[] info = objType.GetFields(BindingFlags.Public | BindingFlags.Static);
// Display the Result Console.Write("Fields of current type is as Follow: "); for (int i = 0; i < info.Length; i++) Console.WriteLine(" {0}", info[i]); }
// 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; public static int id = 02; } ```
Output:
```cs Fields of current type is as Follow: System.Int32 id
```
例 2: 对于如果没有定义公共字段
```cs // C# program to demonstrate the // Type.GetFields(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 array of Fields by // using GetField() Method FieldInfo[] info = objType.GetFields();
// Display the Result Console.Write("Public Fields of current type is as follow: "); if (info.Length != 0) { for (int i = 0; i < info.Length; i++) Console.WriteLine(" {0}", info[i]); } else Console.WriteLine("No public fields are defined for the current Type."); }
// 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 { } ```
Output:
```cs Public Fields of current type is as follow: No public fields are defined for the current Type.
```
方法
此方法用于搜索为当前类型定义的字段，当在派生类约束中重写时，使用指定的绑定。
语法:公共抽象系统。反射。字段信息[]获取字段(系统。反射. binding flags binding attr)； 这里， bindingAttr 是一个由一个或多个 BindingFlags 组成的位掩码，指定如何进行搜索，或者返回 null 的 Zero。
返回值:该方法返回一个 FieldInfo 对象数组，该数组表示为当前类型定义的所有与指定绑定约束相匹配的字段。或者，如果没有为当前类型定义字段，或者定义的字段都不匹配绑定约束，则为类型 FieldInfo 的空数组。
以下程序说明了上述方法的使用:
例 1:
```cs // 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);
// Creating 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:
```cs FieldInfo is - System.String Name
```
示例 2: 适用于参数异常
```cs // C# program to demonstrate the // Type.GetFields(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(Book);
// Creating try-catch block for handling Exception try {
// Getting array of Fields by // using GetField() Method FieldInfo[] info = objType.GetFields(BindingFlags.NonPublic | BindingFlags.Instance);
// Display the Result Console.WriteLine("Fields of current type is as follow :-"); for(int i=0; i<info.Length; i++) Console.WriteLine(" {0}",info[i]); }
// 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 Book { public string Name = "Element of Physics"; public string Author = "R.S. Agrwal"; public static int Price = 500; private string metadata = "djdieeiie";
} ```
Output:
```cs FieldInfo is - System.String Name
```
参考:
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