Exception Handling

1. Exception thrown by a catch cannot be caught by the following catch blocks at the same level.
//catch{} can only catch those exceptions throw from try{}

public class TestClass{
   public static void main(String args[]){
      try{
         m1();
      }catch(IndexOutOfBoundsException e){
         System.out.println("1");
         throw new NullPointerException();
      }catch(NullPointerException e){
         System.out.println("2");
         return;
      }catch (Exception e) {
         System.out.println("3");
      }finally{
         System.out.println("4");
      }
      System.out.println("END");//catch block throw NullPointerException.

   }
   // IndexOutOfBoundsException is a subclass of RuntimeException.
   static void m1(){
      System.out.println("m1 Starts");
      throw new IndexOutOfBoundsException( "Big Bang " );
   }
}

2. You can apply a label to any code block or a block level statement (such as a for statement) but not to individual statement such as loop X : int i = 10;

      loop :         // 1
      {
         System.out.println("Loop Lable line");
               break loop;       // 2
      }

3. Either throws or catch{} is required if there was exception

class TestClass{
 public static void main(String args[]) throws Exception{
  try{
   m1();
   System.out.println("A");
  } //这里没有catch block 但是method throws Exception，所以没有compile error
  finally{
   System.out.println("B");
  }
  System.out.println("C");
 }
 public static void m1() throws Exception { throw new Exception(); }
}