Java Field setBoolean()用法及代碼示例

java.lang.reflect.Field的setBoolean()方法用於將字段的值設置為指定對象上的布爾值。當需要將對象的字段的值設置為布爾值時，可以使用此方法在對象上設置值。

用法:

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

參數：此方法接受兩個參數：

obj：是應該修改其字段的對象，並且
z：這是要修改的obj字段的新值。

返回值：此方法不返回任何內容。

異常：此方法引發以下異常：

IllegalAccessException：如果此Field對象正在實施Java語言訪問控製，並且基礎字段是不可訪問的或最終的。
IllegalArgumentException：如果指定的對象不是聲明基礎字段(或其子類或實現者)的類或接口的實例，或者展開的轉換失敗。
NullPointerException ：如果指定的對象為null並且該字段是實例字段。
ExceptionInInitializerError：如果此方法引發的初始化失敗。

以下示例程序旨在說明setBoolean()方法：
示例1:

// 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; 
}

輸出：

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

示例2:

// 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; 
}

輸出：

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

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

相關用法

注：本文由純淨天空篩選整理自AmanSingh2210大神的英文原創作品 Field setBoolean() 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。