Java 反射和 scala 类

Question

给定以下 scala 类:

class Student (_name:String, _id:Long) {

private var name:String = _name;
private var id:Long = _id;

// 2nd C'tor
def this(_name:String) = this(_name,0);

// 3rd C'tor
def this(_id:Long) = this("No Name",_id);

def printDetails() {

  println("The student's name is : " + name);
  println("The student's id is : " + id);

}

}

以及以下 Java 类:

public class StudentReflectionDemo {

public static void main (String[] args) {

    try {
        Class cl = Class.forName("ClassesAndObjects.Student");
        Method[] methods = cl.getMethods();
        Field[] fields = cl.getFields();

        System.out.println("The methods of the Student class are : ");

        for (int i = 0 ; i < methods.length; i++) {
            System.out.println(methods[i]);
        }

        System.out.println("The fields of the Student class are : ");

        for (int i = 0 ; i < fields.length; i++) {
            System.out.println(fields[i]);
        }

    }
    catch(ClassNotFoundException e) {
        e.printStackTrace();
    }


}

}

它确实正确输出了 Student 类方法，但没有打印 Student 类字段..

我在这里缺少什么？

谢谢

Answer 1

在 Java 中，getFields() 方法仅返回 public 字段。要获取所有字段，请使用 getDeclaredFields() ，它将返回直接在类上声明的所有字段。