How to set the value of an attribute in java reflection

Setting method: 1. Create a sample object; 2. Select the field to be modified by judging the field name; 3. Use the field.set method to set the new field value; 4. Print the modified object. Can.

Operating system for this tutorial: Windows 10 system, Dell G3 computer.

In Java, it is also feasible to set the value of object properties through reflection. Here is an extended example that demonstrates how to set the value of an object property using Java reflection:

import java.lang.reflect.Field;
public class ReflectExample {
    public static void main(String[] args) throws IllegalAccessException {
        // 创建一个示例对象
        Person person = new Person("John", 25, "123 Main St");
        // 获取Class对象
        Class<?> clazz = person.getClass();
        // 获取类的所有字段（包括私有字段）
        Field[] fields = clazz.getDeclaredFields();
        // 遍历字段数组
        for (Field field : fields) {
            // 设置字段为可访问，即使是私有字段也可以访问
            field.setAccessible(true);
            // 获取字段的名称
            String fieldName = field.getName();
            // 获取字段的值
            Object fieldValue = field.get(person);
            // 打印字段名和值
            System.out.println(fieldName + ": " + fieldValue);
            // 修改字段的值
            if (fieldName.equals("age")) {
                field.set(person, 30); // 设置新的年龄值
            }
        }
        // 打印修改后的对象
        System.out.println("Modified Person: " + person);
    }
}
// 示例类
class Person {
    private String name;
    private int age;
    private String address;
    public Person(String name, int age, String address) {
        this.name = name;
        this.age = age;
        this.address = address;
    }
    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                '}';
    }
}

In the above example, we have added the part to modify the field value. By judging the field name, we select the field to be modified (in this case the "age" field), and then use the field.set method to set the new field value. Finally, print the modified object and you will see that the age has been updated.

It should be noted that you also need to be careful when using reflection to modify field values, because this may cause the object to be in an inconsistent state. In practical applications, it is better to modify the state of an object through public methods rather than directly through reflection operations.

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