Java Field getDeclaringClass()用法及代碼示例

java.lang.reflect.Field的getDeclaringClass()方法用於獲取Class對象，該對象聲明此Field對象表示的字段。如果存在Field對象，並且我們想要獲取類對象，則可以使用此方法獲取該類對象。

用法:

public Class<T> getDeclaringClass()

參數：此方法不接受任何內容。

返回值：此方法返回一個對象，該對象表示基礎成員的聲明類。

以下示例程序旨在說明getDeclaringClass()方法：
示例1:

// Java program to demonstrate the above method 
  
import java.lang.reflect.Field; 
  
public class GFG { 
  
    public static void main(String[] args) 
        throws NoSuchFieldException, 
               SecurityException 
    { 
  
        // Get the value field object 
        Field field 
            = User.class
                  .getField("identificationChar"); 
  
        // get the declaring class object 
        Class declaringClass 
            = field.getDeclaringClass(); 
  
        // print result 
        System.out.println("Declaring Class"
                           + " for Field Object: "
                           + declaringClass); 
    } 
} 
  
// sample User class 
class User { 
  
    // static char values 
    public static char identificationChar = 'E'; 
    public static char selectionChar = 'A'; 
    public static String name = "Aman"; 
  
    // getter and setter methods 
    public static char getIdentificationChar() 
    { 
        return identificationChar; 
    } 
  
    public static void
    setIdentificationChar(char identificationChar) 
    { 
        User.identificationChar = identificationChar; 
    } 
  
    public static char getSelectionChar() 
    { 
        return selectionChar; 
    } 
  
    public static void
    setSelectionChar(char selectionChar) 
    { 
        User.selectionChar = selectionChar; 
    } 
  
    public static String getName() 
    { 
        return name; 
    } 
  
    public static void setName(String name) 
    { 
        User.name = name; 
    } 
}

輸出：

Declaring Class for Field Object: class User

示例2:

// Java program to demonstrate the above method 
  
import java.lang.reflect.Field; 
  
import java.lang.reflect.Field; 
  
public class GFG { 
  
    public static void main(String[] args) 
        throws NoSuchFieldException, 
               SecurityException 
    { 
  
        // Get the value field object 
        Field field 
            = Alphabets.class.getField("value"); 
  
        // get the declaring class object 
        Class declaringClass 
            = field.getDeclaringClass(); 
  
        // print result 
        System.out.println("Declaring Class: "
                           + declaringClass); 
    } 
  
    // Alphabets class 
    static class Alphabets { 
  
        // char field 
        public static char value = 'Q'; 
  
        // getter and setter methods 
        public static char getValue() 
        { 
            return value; 
        } 
  
        public static void setValue(char value) 
        { 
            Alphabets.value = value; 
        } 
    } 
}

輸出：

Declaring Class: class GFG$Alphabets

參考文獻： https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Field.html#getDeclaringClass–

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