大家帮忙看下这段关于代理的代码，为什么会出现异常呢？ - 黑马程序员技术交流社区

package cn.itcast.day3;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Collection;
public class ActiveProxy {
public static void main(String[] args) throws Exception{
Class clazzProxy = Proxy.getProxyClass(Collection.class.getClassLoader(), Collection.class);
System.out.println(clazzProxy.getName());
System.out.println("----------begin constructors list----------");
Constructor[] constructors = clazzProxy.getConstructors();
for(Constructor constructor : constructors){
String name = constructor.getName();
StringBuilder sBuilder = new StringBuilder(name);
sBuilder.append('(');
Class[] clazzParams = constructor.getParameterTypes();
for(Class clazzParam : clazzParams){
sBuilder.append(clazzParam.getName()).append(',');
}
if(clazzParams!=null && clazzParams.length != 0)
sBuilder.deleteCharAt(sBuilder.length()-1);
sBuilder.append(')');
System.out.println(sBuilder.toString());
}
System.out.println("----------begin methods list----------");
Method[] methods = clazzProxy.getMethods();
for(Method method : methods){
String name = method.getName();
StringBuilder sBuilder = new StringBuilder(name);
sBuilder.append('(');
Class[] clazzParams = method.getParameterTypes();
for(Class clazzParam : clazzParams){
sBuilder.append(clazzParam.getName()).append(',');
}
if(clazzParams!=null && clazzParams.length != 0)
sBuilder.deleteCharAt(sBuilder.length()-1);
sBuilder.append(')');
System.out.println(sBuilder.toString());
}
System.out.println("----------begin create instance object----------");
Constructor constructor = clazzProxy.getConstructor(InvocationHandler.class);
Collection proxy = (Collection)constructor.newInstance(new InvocationHandler(){
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
return null;
}
});
System.out.println(proxy);
proxy.clear();
}
}

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