使用反射报异常：object is not an instance of declaring class解决方案

在使用反射执行一个方法时常遇到object is not an instance of declaring class的异常，如下代码：view plaincopy to clipboardprint?

Java代码

import java.lang.reflect.Method;    
import java.text.SimpleDateFormat;    
import java.util.Date;    
   
   
   
import cn.rdt.famework.frame.config.FrameConstant;    
   
public class PrimaryKeyUtils {    
 //    
    public    synchronized String getPrimaryKey() {    
        String pk = "";    
        StringBuffer primaryKey = new StringBuffer(new SimpleDateFormat(    
                "yyMMddHHmmssSSS").format(new Date()));    
        int tpk = FrameConstant.PRIMARY_KEY;    
        if (tpk < 9999) {    
            tpk++;    
        } else {    
            tpk = 1000;    
        }    
        FrameConstant.PRIMARY_KEY = tpk;    
        pk = primaryKey.append(String.valueOf(tpk)).toString();    
        primaryKey = null;    
         
        return pk;    
    }    
   
    public String GetPrimaryKey(String mothed){    
        String primaryKey = "";    
        try {    
            Class c = PrimaryKeyUtils.class;    
            Method m = c.getMethod(mothed,new Class[]{});    
//          Object obj=c.newInstance();    
            m.invoke(mothed,null);    
            primaryKey = String.valueOf(m.invoke(c.newInstance() ,new Object[]{}));    
        } catch (Exception e) {    
            e.printStackTrace();    
        }     
        return primaryKey;    
    }    
    public static void main(String[] args) {    
         
        PrimaryKeyUtils primaryKey = new PrimaryKeyUtils();    
        System.out.println(primaryKey.GetPrimaryKey("getPrimaryKey"));    
    }    
}   
import java.lang.reflect.Method; 
import java.text.SimpleDateFormat; 
import java.util.Date; 
 
 
 
import cn.rdt.famework.frame.config.FrameConstant; 
 
public class PrimaryKeyUtils { 
 // 
    public    synchronized String getPrimaryKey() { 
        String pk = ""; 
        StringBuffer primaryKey = new StringBuffer(new SimpleDateFormat( 
                "yyMMddHHmmssSSS").format(new Date())); 
        int tpk = FrameConstant.PRIMARY_KEY; 
        if (tpk < 9999) { 
            tpk++; 
        } else { 
            tpk = 1000; 
        } 
        FrameConstant.PRIMARY_KEY = tpk; 
        pk = primaryKey.append(String.valueOf(tpk)).toString(); 
        primaryKey = null; 
      
        return pk; 
    } 
 
    public String GetPrimaryKey(String mothed){ 
        String primaryKey = ""; 
        try { 
            Class c = PrimaryKeyUtils.class; 
            Method m = c.getMethod(mothed,new Class[]{}); 
//          Object obj=c.newInstance(); 
            m.invoke(mothed,null); 
            primaryKey = String.valueOf(m.invoke(c.newInstance() ,new Object[]{})); 
        } catch (Exception e) { 
            e.printStackTrace(); 
        }  
        return primaryKey; 
    } 
    public static void main(String[] args) { 
      
        PrimaryKeyUtils primaryKey = new PrimaryKeyUtils(); 
        System.out.println(primaryKey.GetPrimaryKey("getPrimaryKey")); 
    } 
} 
  
 
 第34行会报object is not an instance of declaring class错 对象不是声明类的一个实例。解决办法如下： 
 
第一种：反射执行的方法 getPrimaryKey() 改成静态的 
 
第二种：在执行方法前先实例化类。m.invoke(mothed,null)改为m.invoke(c.newInstance(),null)或者m.invoke(new PrimaryKeyUtils(),null) 
 
 
本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/yeson6/archive/2011/01/14/6138963.aspx