The Big Programming Thread - Page 410

// recursive computation of sum of ages of all players in the list
int sumAge(PlayerList list)
{
    if(firstPlayer.getNext() == null)
    {
        return firstPlayer.getAge();
    }
else
    {
        return head().getAge() + sumAge(tail());	
    }
}

PlayerList tail()
{
    PlayerList list = new PlayerList(head().getNext());
    if(list.head() == null)
    {
        final PlayerList empty = new PlayerList();
        return empty;
    }
    return list;
}

boolean firstLine = true;

while (some condition) {
    if (firstLine) {
         // do something
        firstLine = false;
    }
    else {
       // deal with next lines
   }
}

while (some condition) {
     if (numberOfLines == 1) {
         // do something
     }
     else {
         // deal with next lines
     }
}

Exception in thread "main" java.lang.StackOverflowError
	at PlayerList.<init>(PlayerList.java:12)
	at PlayerList.tail(PlayerList.java:36)
	at PlayerList.sumAge(PlayerList.java:115)
	at PlayerList.sumAge(PlayerList.java:115)
	at PlayerList.sumAge(PlayerList.java:115)
	at PlayerList.sumAge(PlayerList.java:115)

int sumAge(PlayerList list){
    //stuff
}

int sumAge(){
    return sumAge(this);
}
// is called in main with
players.sumAge();

int sumAge(PlayerList list){
    //stuff
}

int sumAge(){
    return sumAge(this);
}
// is called in main with
players.sumAge();

PlayerList a;
PlayerList b;   // pretend these have stuff in it

a.sumAge(b); // performs the operation on PlayerList b (I assume summing up the ages...)
a.sumAge();   // calls the non-parameterized one, then falls back to the parameterized method

// Basically...

a.sumAge() == a.sumAge(a);

On December 20 2013 00:24 darkness wrote:
I know it's a slight detail, but I'd like to read some opinions. Let's say you need to count lines but you need to do something specific only for the 1st line, is it better to:

boolean firstLine = true;

while (some condition) {
    if (firstLine) {
         // do something
        firstLine = false;
    }
    else {
       // deal with next lines
   }
}

or is it better to:

while (some condition) {
     if (numberOfLines == 1) {
         // do something
     }
     else {
         // deal with next lines
     }
}

As I said, I know it's a minor detail but I'd rather do it properly. I know people say "don't use magic numbers", hence my uncertainty here.

boolean firstLine = true;

while (some condition) {
    if (firstLine) {
         // do something
        firstLine = false;
    }
    
    // do something else for all lines including first
}