Re: Java exceptions using recursive method

From:
Patricia Shanahan <pats@acm.org>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 22 Apr 2008 21:28:45 -0700
Message-ID:
<fumdtu$2bun$1@ihnp4.ucsd.edu>
Rodusa wrote:

 I am a beginner in java and I am having difficulty in understanding
the output below which uses exceptions and recursion. So far I was
able to understand the logic until line 10. After that I am lost. I
don't understand why is i being decremented? first it printed rec 1,
rec 2 , rec 3 and when it reached the exception it started to
decrement i like 3, 2, 1.

Rod

Output:

1. A(int)
2. B(int)
3. A()
4. B()
5. C()
6. 2
7. rec 1
8. rec 2
9. rec 3
10. Foo excepted
11. Handled in C -> i:3
12. Finally
13. Handled in C -> i:2
14. Finally
15. Handled in C -> i:1
16. Finally
17. Handled in Main

....

     public void rec(int i) throws Exception{
        System.out.println("rec " + i);
        try{
            if(i==3)
                foo();
            else
                rec(i+1);
        } catch(Exception e){
            System.out.println("Handled in C -> i:" +i);
            throw e;
        } finally {
            System.out.println("Finally");
        }
    }
....

The stack can contain several invocations of rec, each with its own
value of i. Nothing is decrementing i, you are just getting reports from
older rec invocations.

Patricia

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