异常

异常有两类：exception和error
throw用于抛出一个异常，throws用于抛出很多异常
public class ThrowDemo{
public static void main(String args[])throws IOException{
....
}
}
pbulic class ThrowDemo{
public static void main(String args[]){
try{
  try{
   System.out.println("我要自己制造异常了.....");
   throw new IOException("FirstException");
  }catch(IOException a){
   System.out.println("捕捉到了："+a);
   throw new NumberFormatException("SecondException");
  }
}catch(NumberFormatException e){
   System.out.println("我又捕捉到了："+e);
}
}
}