Question

在meth2()下面的代码块中抛出ExcepOne和ExcepTwo，自定义异常，扩展Exception，以便检查它们。但是，当我碰巧为IOException编写另一个catch块时，我收到一个编译错误，指出IOException已被捕获。为什么会显示出来？它被抓到了哪里？

 public class ExceptionConcepts {

/**
 * @param args the command line arguments
 */
public static void main(String[] args) throws ExcepOne{

    System.out.println("In main method");
    try{
    meth1();
    }catch(ExcepOne e1)
    {
        System.out.println("Finally caught ExcepOne");
    }
}
public static void meth1() throws ExcepOne{
   try{
    meth2();
   }catch(ExcepTwo e2)
   {
       System.out.println("In meth1 catch for Exceptwo");
       throw new ExcepOne("1ond");
   }

    catch(ExcepOne e1)
   {
       System.out.println("In meth1 catch for ExcepOne");
   }
    catch(IOException ie) // I get a compilation error here
     {

     }
 }
public static void meth2() throws ExcepOne,ExcepTwo{


  int i=-1;
  try{
  if(i<0)
      throw new ExcepOne("one");
   else
      throw new ExcepTwo("two");
  }

  catch(ExcepTwo e1)
  {
      System.out.println("in catch of ExcepTwo");
      throw new ExcepTwo("2");
  }
  catch(ExcepOne e2)
  {
      System.out.println("in catch of ExcepOne");
      throw new ExcepOne("1");
  }
  finally
  {
      System.out.println("I am finally");
      throw new ExcepTwo("2");
  }
 }
}

public class ExcepOne extends Exception()
{
public ExcepOne(String msg)
 {
 super(msg);
 }
} 
public class ExcepTwo extends Exception()
{
public ExcepTwo(String msg)
 {
super(msg);
 }
}

Answer 1

你错过了：

import java.io.IOException;

当你将它添加到你的来源时，会发生以下两件事之一：
- 如果try块可以抛出IOException，程序将编译。
- 否则你将得到汇编error: exception IOException is never thrown in body of corresponding try statement

显示已处理的某些未处理的已检查异常的异常

1 个答案: