try--catch语句的catch问题

lass ExceptionTest{

public static void main(String args[]){

try{

methodA();

}

catch(IOException e){

System.out.println("caught IOException");

}

catch(Exception e){

System.out.println("caught Exception");

}

}

}

1. If methodA() throws a IOException, what is the result?

答案：caught IOException

2.If we change the sequence of catch,what’s the result？（更换两个catch的顺序，结果如何）

答案：编译错误

Unreachable catch block for IOException. It is already handled by the catch block for Exception

无法到达的catch块IOException异常。他已经被IOException异常的catch块已经被处理、

如果catch要捕获的异常量是同一种异常或者存在继承关系，则要将捕获子异常放在语句最前面 ，否则编译报错