Should try…catch go inside or outside a loop?

Question

I have a loop that looks something like this:

for (int i = 0; i < max; i++) {
    String myString = ...;
    float myNum = Float.parseFloat(myString);
            


        

Answer 1

While performance might be the same and what "looks" better is very subjective, there is still a pretty big difference in functionality. Take the following example:

Integer j = 0;
    try {
        while (true) {
            ++j;

            if (j == 20) { throw new Exception(); }
            if (j%4 == 0) { System.out.println(j); }
            if (j == 40) { break; }
        }
    } catch (Exception e) {
        System.out.println("in catch block");
    }

The while loop is inside the try catch block, the variable 'j' is incremented until it hits 40, printed out when j mod 4 is zero and an exception is thrown when j hits 20.

Before any details, here the other example:

Integer i = 0;
    while (true) {
        try {
            ++i;

            if (i == 20) { throw new Exception(); }
            if (i%4 == 0) { System.out.println(i); }
            if (i == 40) { break; }

        } catch (Exception e) { System.out.println("in catch block"); }
    }

Same logic as above, only difference is that the try/catch block is now inside the while loop.

Here comes the output (while in try/catch):

4
8
12 
16
in catch block

And the other output (try/catch in while):

4
8
12
16
in catch block
24
28
32
36
40

There you have quite a significant difference:

while in try/catch breaks out of the loop

try/catch in while keeps the loop active