Java中的字段 setInt() 方法及示例

Java.lang.reflect.Field的setInt()方法用于将字段的值设置为指定对象上的 int。当您需要将对象字段的值设置为 int 时，您可以使用此方法设置对象的值。

句法：

public void setInt(Object obj, int i)
            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
• i ：这是被修改的 obj 字段的新值。

Return ：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。

下面的程序说明了 setInt() 方法：
方案一：

// Java program to illustrate setInt() 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 salary
        System.out.println(
            "Value of salary before "
            + "applying setInt is "
            + emp.salary);
  
        // Get the  field object
        Field field = Employee.class.getField("salary");
  
        // Apply setInt Method
        field.setInt(emp, 2243599);
  
        // print value of salary
        System.out.println(
            "Value of salary after "
            + "applying setInt is "
            + emp.salary);
  
        // print value of uniqueNo
        System.out.println(
            "Value of uniqueNo before "
            + "applying setInt is "
            + emp.uniqueNo);
  
        // Get the field object
        field = Employee.class.getField("uniqueNo");
  
        // Apply setInt Method
        field.setInt(emp, 123434);
  
        // print value of uniqueNo
        System.out.println(
            "Value of uniqueNo after "
            + "applying setInt is "
            + emp.uniqueNo);
    }
}
  
// sample class
class Employee {
  
    // static int values
    public static int uniqueNo = 234289;
    public static int salary = 1125213;
}

输出：

Value of salary before applying setInt is 1125213
Value of salary after applying setInt is 2243599
Value of uniqueNo before applying setInt is 234289
Value of uniqueNo after applying setInt is 123434

方案二：

// Java program to illustrate setInt() method
  
import java.lang.reflect.Field;
  
public class GFG {
  
    public static void main(String[] args)
        throws Exception
    {
  
        // create Numbers object
        Numbers no = new Numbers();
  
        // Get the value field object
        Field field = Numbers.class
                          .getField("value");
  
        // Apply setInt Method
        field.setInt(no, 53266);
  
        // print value of isActive
        System.out.println(
            "Value after "
            + "applying setInt is "
            + Numbers.value);
    }
}
  
// sample Numbers class
class Numbers {
  
    // static int value
    public static int value = 13685;
}

输出：

Value after applying setInt is 53266

参考： https: Java/lang/reflect/Field.html#setInt-java.lang.Object-int-