Java Field getFloat()用法及代码示例

java.lang.reflect.Field的getFloat()方法用于获取必须为静态或实例字段类型的float值。此方法还用于获取通过扩展转换可转换为float类型的另一个原始类型的值。当类包含静态或实例浮点型字段并且我们想要获取该字段的值时，可以使用此方法返回Field的值。

用法:

public float getFloat(Object obj)
             throws IllegalArgumentException,
                    IllegalAccessException

参数：此方法接受单个参数obj，它是要从中提取浮点值的对象。

返回值：此方法返回转换为float类型的字段的值。

异常：此方法引发以下异常：

IllegalAccessException：如果Field对象正在强制执行Java语言访问控制并且基础字段不可访问，则抛出此异常。
IllegalArgumentException：如果指定的对象不是声明基础字段的类或接口的实例，或者如果不能通过扩展转换将字段值转换为float类型，则抛出此异常。
NullPointerException ：如果指定对象为null并且该字段是实例字段，则抛出此异常。
ExceptionInInitializerError：如果此方法引发的初始化失败，则抛出此异常。

以下示例程序旨在说明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; 
    } 
}

输出：

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; 
        } 
    } 
}

输出：

Value: 1.2343212E8

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

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注：本文由纯净天空筛选整理自AmanSingh2210大神的英文原创作品 Field getFloat() method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。