Java Field setChar()用法及代码示例

java.lang.reflect.Field的setChar()方法用于将字段的值设置为指定对象上的char。当需要将对象的字段值设置为char时，可以使用此方法在Object上设置值。

用法:

public void setChar(Object obj, char c)
            throws IllegalArgumentException,
                   IllegalAccessException

参数：此方法接受接受两个参数：

obj：是应该修改其字段的对象，并且
c：这是要修改的obj字段的新值。

返回：此方法不返回任何内容。

异常：此方法引发以下异常：

IllegalAccessException：如果此Field对象正在强制执行Java语言访问控制，并且基础字段是不可访问的或最终的。
IllegalArgumentException：如果指定的对象不是声明基础字段(或其子类或实现者)的类或接口的实例，或者展开转换失败。
NullPointerException：如果指定的对象为null，并且该字段是实例字段。
ExceptionInInitializerError：如果此方法引发的初始化失败。

以下示例程序旨在说明setChar()方法：
示例1:

// Java program to illustrate setByte() method 
  
// program illustrate setChar() 
import java.lang.reflect.Field; 
  
public class GFG { 
  
    public static void main(String[] args) 
        throws Exception 
    { 
  
        // create user object 
        Employee emp = new Employee(); 
  
        // print value of lastNamePrefix 
        System.out.println( 
            "Value of lastNamePrefix before "
            + "applying setChar is "
            + emp.lastNamePrefix); 
  
        // Get the marks field object 
        Field field = Employee.class
                          .getField("lastNamePrefix"); 
  
        // Apply setChar Method 
        field.setChar(emp, 'B'); 
  
        // print value of lastNamePrefix 
        System.out.println( 
            "Value of lastNamePrefix after "
            + "applying setChar is "
            + emp.lastNamePrefix); 
  
        // print value of firstNamePrefix 
        System.out.println( 
            "Value of firstNamePrefix before "
            + "applying setChar is "
            + emp.firstNamePrefix); 
  
        // Get the marks field object 
        field = Employee.class
                    .getField("firstNamePrefix"); 
  
        // Apply setChar Method 
        field.setChar(emp, 'Z'); 
  
        // print value of firstNamePrefix 
        System.out.println( 
            "Value of firstNamePrefix after "
            + "applying setChar is "
            + emp.firstNamePrefix); 
    } 
} 
  
// sample class 
class Employee { 
  
    // static char values 
    public static char firstNamePrefix = 'A'; 
    public static char lastNamePrefix = 'S'; 
}

输出：

Value of lastNamePrefix before applying setChar is S
Value of lastNamePrefix after applying setChar is B
Value of firstNamePrefix before applying setChar is A
Value of firstNamePrefix after applying setChar is Z

示例2:

// Java program to illustrate setChar() method 
  
import java.lang.reflect.Field; 
  
public class GFG { 
  
    public static void main(String[] args) 
        throws Exception 
    { 
  
        // create user object 
        User user = new User(); 
  
        // Get the id field object 
        Field field = User.class
                          .getField("id"); 
  
        // Apply setChar Method 
        field.setChar(user, 'A'); 
  
        // print value of isActive 
        System.out.println("Value after "
                           + "applying setChar is "
                           + user.id); 
    } 
} 
  
// sample User class 
class User { 
  
    // static char values 
    public static char id = 'Z'; 
}

输出：

Value after applying setChar is A

参考： https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Field.html#setChar-java.lang.Object-char-

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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 setChar() 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。