Java 中的 Field setChar()方法，示例
原文:https://www . geesforgeks . org/field-setchar-method-in-Java-with-examples/
setChar() 方法的 java.lang.reflect.Field 用于将字段的值设置为指定对象上的一个字符。当需要将对象字段的值设置为字符时，可以使用此方法在对象上设置值。
语法:
public void setChar(Object obj, char c)
throws IllegalArgumentException,
IllegalAccessException
参数:该方法接受两个参数:
- obj :哪个对象的字段应该被修改
- c :是正在修改的 obj 字段的新值。
返回:此方法不返回任何内容。
异常:该方法抛出如下异常:
- IllegalAccessException:如果此字段对象正在实施 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，或者如果展开转换失败。
- NullPointerException:如果指定的对象为空，并且该字段是实例字段。
- ExceptionInInitializerError:如果此方法引发的初始化失败。
下面的程序说明了 setChar()方法: 程序 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';
}
Output:
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
程序 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';
}
Output:
Value after applying setChar is A
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