How can i convert this Do While loop into another sort of loop, a while loop?

Question

public void humanPlay()
 {
if (player1.equalsIgnoreCase("human"))
    System.out.println("It is player 1's turn.");
else
    System.out.println("It is player 2's turn.");

System.out.println("Player 1 score: " + player1Score);
System.out.print("Player 2 score: " + player2Score);

String eitherOr;

  do {
    eitherOr= input.nextLine(); 
    humanRoll();
  } while (eitherOr.isEmpty());

 if (!eitherOr.isEmpty())
    humanHold();

}

This is the whole method, The only thing i am trying to fix is this.

       String eitherOr;
do {
     eitherOr= input.nextLine();    
     humanRoll();
   } while (eitherOr.isEmpty());

It has to accept input multiple times, so each time input is needed to determine what happens, which is why i like the Do While loop, but since it initializes at least once per time, i get an extra roll than needed.

I have tried to do it this way, and various variations of this way:

String eitherOr = input.nextLine();

while(eitherOr.isEmpty());
        humanRoll();

This does not work because it does not ask for the input over again. If i try to put the input.nextline(); into the while loop, it says "eitherOr" is not initialized, and even if i initialize it when i enter input, the command line stays blank, so it does nothing with my input.

Matt Lacey · Accepted Answer · 2011-12-12 04:15:03Z

4

You've got an extraneous semi-colon:

while(eitherOr.isEmpty());
    humanRoll();'

should be:

while(eitherOr.isEmpty())
    humanRoll();

Essentially your version is saying to do nothing while eitherOr.isEmpty() is true and so it never gets to call humanRoll.

answered Dec 12, 2011 at 4:15

Matt Lacey

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3 Comments

Renuz Over a year ago

Well then, it seems like the last hour has been wasted on a semi colon. Thank you, I have not used a while-loop in a while. Due to this misfortune I foresee me re-reading a few chapters. Probably should have been the first thing i checked to be honest.

Renuz Over a year ago

@ LanceySnr The code still works like it did while it was a do while loop, even if there is input, it still creates another roll.

Matt Lacey Over a year ago

Have you used a debugger or similar to check the content of it when there is input? Given the code posted I can't see how it could execute the loop.

mprabhat · Accepted Answer · 2012-02-15 10:00:18Z

1

If your second code snippet you are executing a blank statement as part of your while loop

while(eitherOr.isEmpty());//this semicolon is a blank statement
    humanRoll();

you have to remove this semicolon in order to execute humanRoll as part of loop

while(eitherOr.isEmpty())
    humanRoll();

On a side note use of paranthesis generally avoids such minor issue

while(eitherOr.isEmpty()) {
    humanRoll();
}

In above code its easy to identify if an unintentional semicolon has been introduced or not.

edited Feb 15, 2012 at 10:00

answered Dec 12, 2011 at 4:22

mprabhat

20.3k7 gold badges49 silver badges64 bronze badges

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