Java中的字段 setBoolean() 方法及示例

Java.lang.reflect.Field的setBoolean()方法用于将字段的值设置为指定对象上的布尔值。当您需要将对象字段的值设置为布尔值时，您可以使用此方法在对象上设置值。

句法：

public void setBoolean(Object obj, boolean z)
            throws IllegalArgumentException,
                   IllegalAccessException

参数：此方法接受两个参数：

• obj ：这是应该修改其字段的对象，并且
• z ：这是被修改的 obj 字段的新值。

返回值：此方法不返回任何内容。

异常：此方法抛出以下异常：

• 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。

下面的程序说明了 setBoolean() 方法：
方案一：

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

输出：

Value before applying setBoolean is true
Value after applying setBoolean is false

方案二：

// Java program to illustrate setBoolean() method
  
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 isManager
        System.out.println("Value of isManager before "
                           + "applying setBoolean is "
                           + emp.isManager);
  
        // Get the marks field object
        Field field
            = Employee.class
                  .getField("isManager");
  
        // Apply setBoolean Method
        field.setBoolean(emp, false);
  
        // print value of isActive
        System.out.println("Value of isPresent before "
                           + "applying setBoolean is "
                           + emp.isManager);
  
        // print value of isManager
        System.out.println("Value of isManager before "
                           + "applying setBoolean is "
                           + emp.isPresent);
  
        // Get the marks field object
        field = Employee.class
                    .getField("isPresent");
  
        // Apply setBoolean Method
        field.setBoolean(emp, true);
  
        // print value of isActive
        System.out.println("Value of isPresent before "
                           + "applying setBoolean is "
                           + emp.isPresent);
    }
}
  
// sample User class
class Employee {
  
    // static boolean values
    public static boolean isPresent = false;
    public static boolean isManager = true;
}

输出：

Value of isManager before applying setBoolean is true
Value of isPresent before applying setBoolean is false
Value of isManager before applying setBoolean is false
Value of isPresent before applying setBoolean is true

参考资料： https: Java/lang/reflect/Field.html#setBoolean-java.lang.Object-boolean-