Java Field getFloat()用法及代碼示例

java.lang.reflect.Field的getFloat()方法用於獲取必須為靜態或實例字段類型的float值。此方法還用於獲取通過擴展轉換可轉換為float類型的另一個原始類型的值。當類包含靜態或實例浮點型字段並且我們想要獲取該字段的值時，可以使用此方法返回Field的值。

用法:

public float getFloat(Object obj)
             throws IllegalArgumentException,
                    IllegalAccessException

參數：此方法接受單個參數obj，它是要從中提取浮點值的對象。

返回值：此方法返回轉換為float類型的字段的值。

異常：此方法引發以下異常：

IllegalAccessException：如果Field對象正在強製執行Java語言訪問控製並且基礎字段不可訪問，則拋出此異常。
IllegalArgumentException：如果指定的對象不是聲明基礎字段的類或接口的實例，或者如果不能通過擴展轉換將字段值轉換為float類型，則拋出此異常。
NullPointerException ：如果指定對象為null並且該字段是實例字段，則拋出此異常。
ExceptionInInitializerError：如果此方法引發的初始化失敗，則拋出此異常。

以下示例程序旨在說明getFloat()方法：
示例1:

// Java program to demonstrate the getFloat() method 
  
import java.lang.reflect.Field; 
  
public class GFG { 
  
    public static void main(String[] args) 
        throws NoSuchFieldException, 
               SecurityException, 
               IllegalArgumentException, 
               IllegalAccessException 
    { 
  
        // Create the User class object 
        User user = new User(); 
  
        // Get the marks field object 
        Field field = User.class.getField("Marks"); 
  
        // Apply getFloat Method on User Object 
        // to get the value of Marks field 
        float value = field.getFloat(user); 
  
        // print result 
        System.out.println("Value of float Field"
                           + " Marks is " + value); 
  
        // Now Get the Fees field object 
        field = User.class.getField("Fees"); 
  
        // Apply getFloat Method on User Object 
        // to get the value of Fees field 
        value = field.getFloat(user); 
  
        // print result 
        System.out.println("Value of float Field"
                           + " Fees is " + value); 
    } 
} 
  
// sample User class 
class User { 
  
    // static float values 
    public static float Marks = 94.13f; 
    public static float Fees = 1343413.99f; 
    public static String name = "Aman"; 
  
    public static float getMarks() 
    { 
        return Marks; 
    } 
  
    public static void setMarks(float marks) 
    { 
        Marks = marks; 
    } 
  
    public static float getFees() 
    { 
        return Fees; 
    } 
  
    public static void setFees(float fees) 
    { 
        Fees = fees; 
    } 
  
    public static String getName() 
    { 
        return name; 
    } 
  
    public static void setName(String name) 
    { 
        User.name = name; 
    } 
}

輸出：

Value of float Field Marks is 94.13
Value of float Field Fees is 1343414.0

示例2:

// Java program to demonstrate the getFloat() method 
  
import java.lang.reflect.Field; 
  
public class GFG { 
  
    public static void main(String[] args) 
        throws NoSuchFieldException, 
               SecurityException, 
               IllegalArgumentException, 
               IllegalAccessException 
    { 
  
        // Create the RealNumbers class object 
        RealNumbers real = new RealNumbers(); 
  
        // Get the value field object 
        Field field 
            = RealNumbers.class
                  .getField("value"); 
  
        // Apply getFloat Method on field Object 
        // to get the value of value field 
        float value = field.getFloat(real); 
  
        // print result 
        System.out.println("Value: " + value); 
    } 
  
    // RealNumbers class 
    static class RealNumbers { 
  
        // float field 
        public static float value 
            = 123432123.1234f; 
  
        // getter and setter methods 
        public static float getValue() 
        { 
            return value; 
        } 
  
        public static void setValue(float value) 
        { 
            RealNumbers.value = value; 
        } 
    } 
}

輸出：

Value: 1.2343212E8

參考文獻： https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Field.html#getFloat-java.lang.Object-

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注：本文由純淨天空篩選整理自AmanSingh2210大神的英文原創作品 Field getFloat() method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。