A return statement in a void
method stops running the method and returns back to the calling code. In this example with the input:
numberOfLoops = 4
numberOfIterations = 4
Right after taking the input, you create an array based off of the input and then call the nestedLoops(0)
method:
public static void nestedLoops(int currentLoop) {
if (currentLoop == numberOfLoops) {
printLoops();
return;
}
for (int counter=1;counter<=numberOfIterations;counter++) {
loops[currentLoop] = counter;
nestedLoops(currentLoop + 1);
}
}
The explanation
For starts, let's just ignore the for loop. The if statement checks to see if currentLoop == numberOfLoops
and it does this every time this method is called. Right now currentLoop
is 0 (the value we passed into this method when we called it) and numberOfLoops is 4 (the value we entered at the very beginning) so this is false and none of the code inside is called.
The for loop below the if statement is going to run numberOfIterations
times. In our case, this loop is going to run 4 times. I will write out what happens below in sequential order:
- input is 4, 4
- nestedLoops(0) called- currentLoop = 0
- if evaluates to false
- for loop runs
- loops[0] = 1
- nestedLoops(1)
- if evaluates to false ( 1 != 4)
- for loop runs
- loops[1] = 1
- nestedLoops(2)
- if evaluates to false (2 != 4)
- for loop runs
- loops[2] = 1
- nestedLoops(3)
- if evaluates to false (3 != 4)
- for loop runs
- loops[3] = 1
- nestedLoops(4)
- if evaluates to TRUE (4 == 4)
- loops are printed (all values are 1 right now)
-returns to calling location
-Which is the for loop associated with this indention.
-For loop increments, and then sets loops[3] = 2.
- then this loop finishes
- then this loop finishes
etc. etc.
The return in a void method just means "okay, stop what you're doing and go back to who/whatever called this and move on" In this case its jumping back to previous for loop to keep working.