Question

我无法打印出方法factorial的注释。当我不使factorial返回任何值并将结果打印在方法本身时，它就可以工作。我不是在这里理解这个问题。

import java.io.*;
import java.lang.annotation.Annotation;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.reflect.Method;

@Retention(RetentionPolicy.RUNTIME)

@interface Store
{
int id();
String developerName();
String createdDate();
String Copyrightmessage();
}

public class Ch10LU1Ex2 
{
@Store(id = 1, developerName = "Robin", createdDate = "03/Jan/2013", Copyrightmessage =     "Cannot copy anything")
public static int factorial(int n)
{
    int result;
    if(n==1)
    return 1;
    result = factorial(n-1) * n ;
    return result;

}

public static void main(String[] args) 
{
    try
     {


      Ch10LU1Ex2 ch = new Ch10LU1Ex2();
      System.out.println("Enter any number from 0 to 10 to find factorial:");
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      int ch1 = Integer.parseInt(br.readLine());
      int x = ch.factorial(ch1);
      System.out.println("The factorial is:"+x);
      Method method = ch.getClass().getMethod("factorial");
      Annotation[] annos = method.getAnnotations();
      for(int i=0; i<annos.length;i++)
      {
        System.out.println(annos[i]);
      }
     }
    catch(Exception e)
    {
        e.printStackTrace();
    }
}
}

Answer 1

您必须指明参数的类型：

Method method = Ch10LU1Ex2.class.getMethod("factorial", Integer.TYPE);

否则你只会获得NoSuchMethodException。

以下是“1”获得的输出：

Enter any number from 0 to 10 to find factorial:
1
The factorial is:1
@Store(id=1, developerName=Robin, createdDate=03/Jan/2013, 
Copyrightmessage=Cannot copy anything)

Java注释：无法通过反射找到方法

1 个答案: