ข้อยกเว้นทำงานอย่างไร

class ExceptionExampleOriginal
{


    public static void main(String[] args)
    {
        System.out.println("main begin");
        try
        {
            System.out.println("main before call");

            method1();



            System.out.println("main after call");
        }
        catch (RuntimeException e)
        {


            String s = e.getMessage();
            System.out.println(s);
        }
        System.out.println("main end");
    }

    public static void method1()
    {
        System.out.println("method1 begin");
        method2();

        System.out.println("method1 end");
    }

    public static void method2()
    {
      System.out.println("method2");
      String s = "Message: Unknown Exception";
      throw new RuntimeException(s);

    }
}

public class ExceptionExample
{
    private static Exception exception = null;

   public static void main(String[] args)
    {
        System.out.println("main begin");


        System.out.println("main before call");

        method1();

        if (exception == null)
        {
            System.out.println("main after call");
        }
        else if (exception instanceof RuntimeException)
        {
            RuntimeException e = (RuntimeException) exception;
            exception = null;
            String s = e.getMessage();
            System.out.println(s);
        }
        System.out.println("main end");
    }

    public static void method1()
    {
        System.out.println("method1 begin");
        method2();
        if (exception != null) return;
        System.out.println("method1 end");
    }

    public static void method2()
    {
        System.out.println("method2");
        String s = "Message: Unknown Exception";
        exception = new RuntimeException(s);
        return;
    }
}