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