return in for loop or outside loop

Question

Today  someone attended me to bad use of the return keyword in Java  I had written a simple for loop to validate that something is in an array  Supposing array is an array of length n  this was my code   for  int i   0  i  lt  array length    i        if  array i     valueToFind            return true          return false    Now someone told me that this is not very good programming because I use the return statement inside a loop and this would cause garbage collection to malfunction  Therefore  better code would be   int i   0  while  i  lt  array length  amp  amp  array i     valueToFind          i    return i    array length    The problem is that I can t come up with a proper explenation of why the first for loop isn t a good practice  Can somebody give me an explanation

User · Answer

The code is valid  i e  will compile and execute  in both cases    One of my lecturers at Uni told us that it is not desirable to have continue  return statements in any loop - for or while  The reason for this is that when examining the code  it is not not immediately clear whether the full length of the loop will be executed or the return or continue will take effect    See Why is continue inside a loop a bad idea  for an example   The key point to keep in mind is that for simple scenarios like this it doesn t  IMO  matter but when you have complex logic determining the return value  the code is  generally  more readable if you have a single return statement instead of several   With regards to the Garbage Collection - I have no idea why this would be an issue

User · Answer

Now someone told me that this is not very good programming because I   use the return statement inside a loop and this would cause garbage   collection to malfunction    That s a bunch of rubbish  Everything inside the method would be cleaned up unless there were other references to it in the class or elsewhere  a reason why encapsulation is important   As a rule of thumb  it s generally better to use one return statement simply because it is easier to figure out where the method will exit   Personally  I would write   Boolean retVal   false  for int i 0  i lt array length    i       if array i   valueToFind            retVal   true          break    Break immediately helps if you are looking through a big array         return retVal

User · Answer

Now someone told me that this is not very good programming because I use the return statement inside a loop and this would cause garbage collection to malfunction     That s incorrect  and suggests you should treat other advice from that person with a degree of skepticism   The mantra of  only have one return statement   or more generally  only one exit point  is important in languages where you have to manage all resources yourself - that way you can make sure you put all your cleanup code in one place   It s much less useful in Java  as soon as you know that you should return  and what the return value should be   just return  That way it s simpler to read - you don t have to take in any of the rest of the method to work out what else is going to happen  other than finally blocks

User · Answer

Since there is no issue with GC  I prefer this  for int i 0  i lt array length    i       if array i     valueToFind          return true

User · Answer

There have been methodologies in all languages advocating for use of a single return statement in any function  However impossible it may be in certain code  some people do strive for that  however  it may end up making your code more complex  as in more lines of code   but on the other hand  somewhat easier to follow  as in logic flow    This will not mess up garbage collection in any way    The better way to do it is to set a boolean value  if you want to listen to him    boolean flag   false  for int i 0  i lt array length    i       if array i     valueToFind            flag   true          break          return flag

User · Answer

Some people argue that a method should have a single point of exit  e g   only one return   Personally  I think that trying to stick to that rule produces code that s harder to read  In your example  as soon as you find what you were looking for  return it immediately  it s clear and it s efficient  Quoting the C2 wiki   The original significance of having a single entry and single exit for a function is that it was part of the original definition of StructuredProgramming as opposed to undisciplined goto SpaghettiCode  and allowed a clean mathematical analysis on that basis  Now that structured programming has long since won the day  no one particularly cares about that anymore  and the rest of the page is largely about best practices and aesthetics and such  not about mathematical analysis of structured programming constructs

[java] return in for loop or outside loop

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