Labelled and Unlabelled controls??

[Joe Harry]

Hi Guys,

Consider the code below from Dan Chisholm,

class JMM120 {
  public static void main (String args[]) {
    int i = 0, j = 0, k = 0;
label1:
    for (; ; )  { i++;
label2:
      do {
        k = i + j;
        switch (k) {
          case 0: continue label2;
          case 1: continue label1;
          case 2: break;
          case 3: break label2;
          case 4: break label1;
          default: break label1;
        }
      } while (++j<5);
    }
    System.out.println(i + "," + j);
}}

Can anyone explain the flow??

Thanks in advance.

[ December 07, 2006: Message edited by: Jothi Shankar Kumar Sankararaj ]
[ December 07, 2006: Message edited by: Jothi Shankar Kumar Sankararaj ]

[Burkhard Hassel]

Hi Jothi,

perhaps put this line immediately over the switch line:
System.out.printf("i:%d j:%d k:%d%n",i,j,k);

I don't show the flow, only where the breaks and continues jump to.

case 0: continue label2;
does not occur (but would jump in between the } and the while).

case 1: continue label1;
jumps to the third argument of the for loop (after the second semikolon).

case 2: break;
jumps after the } of the switch block. From there to the while (j gets incremented).

case 3: break label2;
jumps after the do block, i.e. after the while condition (so j is not incremented). The while condition belongs to the do block!

case 4: break label1;
jumps after the } of the for loop - System.out.

default does not occur.



Output with the additional line is
i:1 j:0 k:1
i:2 j:0 k:2
i:2 j:1 k:3
i:3 j:1 k:4
3,1



Yours,
Bu.

[Joe Harry]

Thanks Bu.