class Person {
  public final String name = "Mike";
}

public static void modify(Object object, String fieldName, Object newFieldValue) throws Exception {
 Field field = object.getClass().getDeclaredField(fieldName);
 
 Field modifiersField = Field.class.getDeclaredField("modifiers");
 modifiersField.setAccessible(true); //Field 的 modifiers 是私有的
 modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
 
 if(!field.isAccessible()) {
  field.setAccessible(true);
 }
 
 field.set(object, newFieldValue);
}

Person person = new Person();
modify(person, "name", "Michael");
System.out.println(person.name); //输出仍然是 Mike

public String getName() {
 return name;
}

public final String name = new String("Mike");

modify(person, "name", "Michael");
System.out.println(person.name) //输出就是 Michael 了

public class TestFinal {
 public static void main(String[] args) throws Exception {
  Person jordan = new Person("Chicago");
 
  modify(jordan , "firstName", "Michael");
  System.out.println(jordan .firstName); //Mike
 
  modify(jordan , "lastName", "Michael");
  System.out.println(jordan.lastName); //Michael
 
  modify(jordan , "age", 51f);
  System.out.println(jordan .age); //50.5
 
  modify(jordan , "height", 1.98f);
  System.out.println(jordan.height); //1.98
 
  modify(jordan, "address", new Address("ccc", "ddd"));
  System.out.println(jordan.address.line1); //ccc
 
  modify(jordan , "city", "Miami");
  System.out.println(jordan.city); //Miami
 }
}
 
class Person {
 public final String firstName = "Mike";
 public final String lastName = new String("Jordan"); //可被有效修改
 public final float age = 50.5f;
 public final Float height = 1.99f; //可被有效修改
 public final Address address = new Address("aaa", "bbb"); //可被有效修改
 
 public final String city; //可被有效修改
 
 public Person(String city) {
  this.city = city;
 }
}
 
final class Address {
 public final String line1;
 public final String line2;
 
 public Address(String line1, String line2) {
  this.line1 = line1;
  this.line2 = line2;
 }
}

private static Logger log = LoggerFactory.getLogger(TestFinal.class);

private static final Logger log = LoggerFactory.getLogger(TestFinal.class);