线程“ main”中的异常java.lang.NoSuchMethodException：

Question

请帮助我找到为什么异常发生在这里。

public class SampleAnnotation
{
    public static void main(String args[]) throws Exception
    {

        Method method = Check.class.getDeclaredMethod("getId", null);
        System.out.println("method:"+method);
        SampleAnnotation1 annotMethd = method.getAnnotation(SampleAnnotation1.class);
        System.out.println(annotMethd.author()+"::"+annotMethd.lastModified());

        method = Check.class.getDeclaredMethod("getId", Integer.class);
        System.out.println("method:"+method);
        annotMethd = method.getAnnotation(SampleAnnotation1.class);
        System.out.println(annotMethd.author()+"::"+annotMethd.lastModified());


    }
}

@Documented
@Retention(value=RetentionPolicy.RUNTIME)
@Target(value={ElementType.CONSTRUCTOR,ElementType.FIELD,ElementType.LOCAL_VARIABLE,ElementType.METHOD,ElementType.PACKAGE,ElementType.PARAMETER,ElementType.TYPE})
@interface SampleAnnotation1 
    {
           String author();
           String lastModified() default "N/A";        

    }
@SampleAnnotation1
( author = "leo",  
  lastModified = "joe"
  )
class Check
{
    @SampleAnnotation1
    ( 
            author = "joe"          
    )
    public int id;

    @SampleAnnotation1
    ( 
            author = "joeidgetter"
    )
    public int getId() {
        return id;
    }
    @SampleAnnotation1
    ( 
            author = "joeidgetterwithint"
    )
    public int getId(int i) {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }       

}

例外情况：

method:public int leo.annotate.Check.getId()
joeidgetter::N/A
Exception in thread "main" java.lang.NoSuchMethodException: leo.annotate.Check.getId(java.lang.Integer)
    at java.lang.Class.getDeclaredMethod(Unknown Source)
    at leo.annotate.SampleAnnotation.main(SampleAnnotation.java:20)

Answer 1

您正在传递一个Integer类参数。

您需要传递一个原语，因为您的方法需要一个原语int 。

采用：

method = Check.class.getDeclaredMethod("getId", int.class);

Answer 2

您使用了Integer.class而您的方法使用了一个int参数，因此应改用int.class 。