catch statements

[Stephen Foy]

Ive been having trouble implementing a catch statement into this method. I want to catch all values but y and n.

Any suggestions?

public void rollDice() {
 
dice generate = new dice();
 
int largest = Integer.MIN_VALUE;
boolean UserRollsAgain = false;
int length = diceRound.length;
int moveRolls = 1;
int counter = 0;
String answer = " ";
 

while (moveRolls <= 3) {// Allows user to play the game 3 times
 
UserRollsAgain = false;
 
if (moveRolls == 2) {
length = diceRound.length - 1; largest = 0;// If second roll then, two dice must be used
}
else if (moveRolls == 3) {
length = diceRound.length - 2; largest = 0; // If third roll then, one dice.
}
 

// Loops program while counter < 2 and user rolls again
 
while (!UserRollsAgain) {
 
System.out.print("Roll "+moveRolls+":  | ");
 
for (int i = 0;i < length;i++) {// Rolls dice and determines highest value
diceRound[i] = generate.diceNumber();// and assigns it to the array values.
System.out.print(diceRound[i]+" | ");
 
if (diceRound[i] > largest) {
largest = diceRound[i];
}
values[i] = largest;
}
 
// If statements, determines whether uses can roll again or not.
 
if (counter < 1) {
System.out.print(" - Keep "+largest+" or roll again? y or n: ");
Scanner in = new Scanner(System.in);
answer = in.nextLine();
System.out.println(" ");
}
 
if (counter == 1) {
System.out.println (" - Your Number is "+largest+" You Have No more rolls\n");
UserRollsAgain = true;
moveRolls++;
counter = 0;
}
 
else if (answer.length() == 1 && answer.charAt(0)=='y') {
counter++;
largest = 0;
UserRollsAgain = false;
}
 
else if (answer.length() == 1 && answer.charAt(0)=='n') {
System.out.println ("(Your Number is "+largest+")\n");
UserRollsAgain = true;
moveRolls++;
}
 
else { System.out.println ("Error\n"); UserRollsAgain = true;}
}
 
}
} // rollDice ends;

Thanks

[Keith Lynn]

I'm a little confused about your question. Are you talking about creating a catch block to handle an exception? Or are you talking about checking values that the user enters with if statements like you have?

[Stephen Foy]

catch block

[Chad Clites]

Errr... a catch block is half of a try/catch block, which as Keith already pointed out, is an error/exception catching block. For instance:

try{
   open myFile
}catch(Exception e){
   print exception   //oops.. something went wrong
}

Are you maybe trying to do something like this?

if (answer.charAt(0) != 'y' && answer.charAt(0) != 'n'{
    then do something here
}

That seems maybe backwards from what it appears that you are trying to do. Could you maybe help us out and explain what you are trying to do?

EDIT: Or are you saying that you want to see if it is a yes or no answer first, and if it isn't, then skip the code altogether?
[ December 13, 2005: Message edited by: C Clites ]

[marc weber]

ste, does this mean you're considering throwing an exception if the user enters something other than 'n' or 'y'?
[ December 13, 2005: Message edited by: marc weber ]

[Stephen Foy]

Yea, if the user enter y, or n, then the program will do something, but anything else throws an exception. I just cant seem to get the catch to work.

[Chad Clites]

I'm not convinced that you want to catch anything, and I'm not sure how to explain to you that I don't think that is what you want to do. A try/catch statement is for catching program errors..

Strictly defined

Definition: An exception is an event that occurs during the execution of a program that disrupts the normal flow of instructions during the execution of a program.

What I think you really want to do is something like as follows:

if input is not 'y' or 'n'
   do something
else
   process code

Some ways of handling bad input are ignoring the input (bad idea), or somehow letting the user know that their input was bad (better). I would consider that a normal event, and not one that disrupts the flow of a program.

Unless you are really interested in generating custom exceptions..

[Stephen Foy]

Thanks, i did do that initially, but the problem is when i put something bad in, it generates the game numbers again. Ill figure it out. Try this and see what i mean. The uses is only allowed 1 roll each turn.

import java.util.*;
 
class diceGame {
 
int[] diceRound = new int[3]; // Holds the random numbers
int[] values = new int[3];  // Holds the highest values
 
/** highestValue
*   Takes the values array, and adds together to return the score of the game.
* @return: returns sum of highest values */
 
public int highestValue() {
int sum = 0;
for (int i = 0;i < values.length;i++) {
sum = ((sum + values[i]));
}
return sum;
}
 
/** diceNumber
* Generates a random number
*@return: returns the randomNumber */
 
int diceNumber() {
int realNum = (int) Math.floor(Math.random() * 6) + 1;
return realNum;
}
 
/** rollDice
*This methid plays the game, it rolls the dice once with 3 random numbers, gives user option
*to keep the highest or roll again, maximum 2 trys, then does this all the way down to one dice
*
*Assigns highest values to array "values".
*/
 

public void rollDice() {
 
diceGame generate = new diceGame();
 
int largest = Integer.MIN_VALUE;
boolean UserRollsAgain = false;
int length = diceRound.length;
int moveRolls = 1;
int counter = 0;
String answer = " ";
 

while (moveRolls <= 3) {// Allows user to play the game 3 times
 
UserRollsAgain = false;
 
if (moveRolls == 2) {
length = diceRound.length - 1; largest = 0;// If second roll then, two dice must be used
}
else if (moveRolls == 3) {
length = diceRound.length - 2; largest = 0; // If third roll then, one dice.
}
 

// Loops program while counter < 2 and user rolls again
 
while (!UserRollsAgain) {
 
System.out.print("Roll "+moveRolls+":  | ");
 
for (int i = 0;i < length;i++) {// Rolls dice and determines highest value
diceRound[i] = generate.diceNumber();// and assigns it to the array values.
System.out.print(diceRound[i]+" | ");
 
if (diceRound[i] > largest) {
largest = diceRound[i];
}
values[i] = largest;
}
 
// If statements, determines whether uses can roll again or not.
 
if (counter < 1) {
System.out.print(" - Keep "+largest+" or roll again? y or n: ");
Scanner in = new Scanner(System.in);
answer = in.nextLine();
System.out.println(" ");
}
 
if (counter == 1) {
System.out.println (" - Your Number is "+largest+" You Have No more rolls\n");
UserRollsAgain = true;
moveRolls++;
counter = 0;
}
 
else if (answer.length() == 1 && answer.charAt(0)=='y'|| answer.charAt(0)=='Y') {
counter++;
largest = 0;
UserRollsAgain = false;
}
 
else if (answer.length() == 1 && answer.charAt(0)=='n' || answer.charAt(0)=='N') {
System.out.println ("(Your Number is "+largest+")\n");
UserRollsAgain = true;
moveRolls++;
}
 
else if (answer.charAt(0) != 'y' || answer.charAt(0) != 'Y' || answer.charAt(0) != 'n' || answer.charAt(0) != 'N') {
System.out.println ("Error\n"); UserRollsAgain = true;
}
}
 
}
} // rollDice ends;
 
/** main method
*runs the game, and displays highest value.
*gives user option to play game again
*/
 

public static void main(String[] args) {
diceGame game = new diceGame();
boolean loopGame = false;
 
while (!loopGame) {
 
System.out.println("\n        [ Dice Game - Stephen Foy ]\n");
 
game.rollDice();
 
System.out.println("             Your Score is: "+game.highestValue()+"\n");
System.out.println("          [    Game Finished    ]\n");
 
System.out.print("Would you like to play again y or n: ");
Scanner in = new Scanner(System.in);
String answer = in.nextLine();
 

if (answer.length() == 1 && answer.charAt(0)=='y') {
loopGame = false;
}
else if (answer.length() == 1 && answer.charAt(0)=='n') {
loopGame = true;
}
 
else { loopGame = true; }
}
}
}

[Chad Clites]

I understand what you are trying to do, and after looking at your code a bit, I'm pretty sure you know what you need to do, although I think some restructuring is called for. I suggest maybe sitting down with your pencil and paper and thinking it through a bit... you have so many loops and whiles that it is hard to keep track of everything.

If I am following your descriptions, basically you have three rolls to get the highest score. On each of the three rolls, you have the option of saving one of the scores. After three rolls, the scores are added, and the score printed.

One place I would look at starting is

while number of rolls is less than three{
   ask to save
   roll again
   increment roll count by one
}

Keep the totals and amount of rolls outside of the loop.. that way they don't get reset each time.

but the problem is when i put something bad in, it generates the game numbers again. Ill figure it out. Try this and see what i mean.

What I would do in this case is that if the user puts in something bad (something other than y or n), then make it default to no (do not save the highest roll). That way, you only need to check if the user chose yes.. so you would have something like:

 
if user chooses y
   save the highest roll
   decrease amount of dice to be rolled next time
else
   don't save any and roll again

Or if you want, you can check if it is a y or n, and if it isn't, prompt the user for a valid input.

Another thing that may be nit-picky... you don't need an array to hold the highest values. Since the values are going to be totaled, why not just keep a single int to keep track of the running score? Then there is no need for a seperate loop to total the scores later. You only need to print out the total.

Also, you don't need an array to hold the rolls either, you just need a single int to hold the highest roll for that round. It is initially a little more tricky to code, but your code will be more simple, and easier to read.

I think the one thing that will help you the most is to use a pencil and paper and draw out your program. It should give you a much clearer idea of what you want to do...

[marc weber]

Originally posted by Chad Clites:
... What I would do in this case is that if the user puts in something bad (something other than y or n), then make it default to no...

Good advice.

[Stephen Foy]

Thanks alot chad, ill ake your advice