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Multiplayer Random Number Guessing Game: How to create random number for each player? [duplicate]

This question already has answers here:
How do I generate random integers within a specific range in Java?
(72 answers)
Closed 3 years ago.
I am creating a random number generator multiplayer game (LAN).
I need help on how to create a code to make each player receive their own random number, and whenever one player guesses a code, the next turn would be a new player. Similar to where the output would show the following,
Fred, Please Guess the random number (integers only!!): 5
TOO LOW
Tom, Please Guess the random number (integers only!!): 95
TOO HIGH
John, Please Guess the random number (integers only!!): 50
TOO LOW
Then when a player guesses correctly, their turn is skipped and the game will end when all players have guessed their numbers, showing the number to guesses each person had, as well as the numbers they guessed previously.
This is what I have so far:
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner keyboard = new Scanner(System.in);
Random myRand = new Random();
ArrayList<Integer> guessedNumbers = new ArrayList();
int x = 0;
int players = 0;
System.out.println("how many players are there?:");
players = checkint(players);
int arraySize = guessedNumbers.size();
int[] numPlayers = new int [players];
boolean play = true;
boolean validGuess = true;
String [] pNames = new String[players];
for (int i = 0; i<players; i++) {
System.out.println("New player, what is your name?:");
pNames[i] = keyboard.nextLine();
}
while(play) {
int randNum = myRand.nextInt(100) + 1;
int numOfGuesses = 0;
do {
System.out.println("Enter what you think the number is between 0 and 100!:");
x= checkint(x);
guessedNumbers.add(x);
if (x < 0) {
System.out.println("we don't accept negative numbers");
if (x > 100) {
System.out.println("that number is above the random number generator range");
}
}
numOfGuesses++;
if (x == randNum) {
System.out.println("that's correct!");
System.out.println("It took you " + numOfGuesses + " tries!");
System.out.print("these are all the numbers you guessed:");
for(int count=0; count<guessedNumbers.size(); count++){
System.out.print(guessedNumbers.get(count) + ",");}
System.out.println("");
boolean playError = true;
//if ("Yes".equals(answer)) {
do {
System.out.println("Would you like to play again: Yes or No");
String answer = keyboard.nextLine();
if (answer.compareToIgnoreCase("yes") == 0) {
play = true;
playError = false;
} else if (answer.compareToIgnoreCase("no") == 0) {
play =false;
playError = false;
System.out.println("Thank you for playing");
} else {
//you messed up
System.out.println("You answer was invalid");
playError = true;
}
} while (playError == true);
}
else if
(x>randNum)
System.out.println("Lower than that!");
else if
(x<randNum)
System.out.println("Higher than that!");
} while (x != randNum);
}}
}
static int checkint(int a) {
int enteredNumber = 0;
Scanner myScanner = new Scanner(System.in);
boolean numberError = false;
String enteredString = "";
do {
try {
enteredString = myScanner.next(); //Read into a string
enteredNumber = Integer.parseInt(enteredString.trim()); //then cast as a integer
numberError = false; //if we haven't bailed out, then the number must be valid.
} catch(Exception e) {
System.out.println("Your entry: \"" + enteredString + "\" is invalid...Please try again");
numberError = true; //Uh-Oh...We have a problem.
}
} while (numberError == true ); //Keep asking the user until the correct number is entered.
return enteredNumber;
}
}

You are doing simple things in a complex way, however, my code can still be replaced by a compressed version but you can understand this better. Following code is doing exactly what you want it to do. I've:
Created Player class, so each player will keep record of guessedNumbers, Number of Guesses and it's name.
You don't have to make tons of variables like pName[], play, validGuesses etc...
I have changed some of the If-Conditions and removed the outer while-loop
Added new round concept, so whenever a player guessed the number, the number got changed.
and much more ....
UPDATED Code: Now each Player has a different random number to guess.
import java.util.*;
public class GuessNumber
{
public static void main(String[] args)
{
// TODO Auto-generated method stub
Scanner keyboard = new Scanner(System.in);
Random myRand = new Random();
ArrayList<Player> players = new ArrayList<Player>();
int x = 0;
System.out.println("how many players are there?:");
int noPlayer = checkint();
boolean validGuess = true , playError = true;
for (int i = 0; i<noPlayer; i++)
{
System.out.println("New player, what is your name?:");
players.add(new Player (keyboard.nextLine()));
}
for (int i = 0; i<noPlayer; i++)
{
players.get(i).number = myRand.nextInt(100) + 1;
}
int i =0; // for chossing different player each time
do
{
System.out.printf(players.get(i).name + " enter what you think the number is between 0 and 100!: ");
x= checkint();
players.get(i).guessedNumbers.add(x);
players.get(i).numOfGuesses++;
if (x == players.get(i).number)
{
System.out.println("That's correct!");
System.out.println("It took you " + players.get(i).numOfGuesses + " tries!");
System.out.print("These are all the numbers you guessed: ");
System.out.println(players.get(i).guessedNumbers);
do
{
System.out.println("Would you like to play again: Yes or No");
String answer = keyboard.nextLine();
if (answer.compareToIgnoreCase("yes") == 0)
{
playError = false;
players.get(i).number = myRand.nextInt(100) + 1; // creates a new random number for second round of the game
System.out.println("\n\n************ " +players.get(i).name + " WON ********");
System.out.println("\n************* SECOND ROUND STARTS **********");
}
else if (answer.compareToIgnoreCase("no") == 0)
{
playError = false;
System.out.println("Thank you for playing");
System.out.println("\n\n************ " +players.get(i).name + " WON ********");
System.out.println("\n************* SECOND ROUND STARTS **********");
players.remove(i);
}
else
{
System.out.println("You answer was invalid");
playError = true;
}
} while (playError);
}
else if (x>players.get(i).number)
System.out.println("Lower than that!");
else if (x<players.get(i).number)
System.out.println("Higher than that!");
if(i == noPlayer-1 || !(playError))
i = 0;
else
i++;
}while (players.size() > 0);
System.out.println("\n\n******************** Every Body Guessed Their Numbers ******************");
}
static int checkint()
{
int enteredNumber = 0;
Scanner myScanner = new Scanner(System.in);
boolean numberError = false;
do
{
try
{
enteredNumber = Integer.parseInt(myScanner.next().trim());
if (enteredNumber < 0 || enteredNumber > 100)
{
System.out.println("Either you entered a negative number or number is above the random number generator range");
numberError = true;
}
else
numberError = false; //if we haven't bailed out, then the number must be valid.
} catch(Exception e)
{
System.out.println("Your entry is invalid...Please try again");
numberError = true; //Uh-Oh...We have a problem.
}
} while (numberError); //Keep asking the user until the correct number is entered.
return enteredNumber;
}
}
// now each player would have its own record.
class Player
{
int numOfGuesses= 0;
ArrayList<Integer> guessedNumbers = new ArrayList<Integer>();
String name = "";
int number = 0;
public Player(String nam)
{
name = nam;
}
}
NOTE: I've added some new lines to output on the screen , once a players wins and want to play again or not. I recommend you to compare your code with mine, so that you'll get a better understanding of your approach vs mine. Do let me know if you find something difficult to understand.

Just use the Random class:
Random ran = new Random();
// Assumes max and min are non-negative.
int randomInt = min + ran.nextInt(max - min + 1);
I referenced here.
How do I generate random integers within a specific range in Java?

Having trouble w/ returning and passing values; "counting"

Our task was to create a guessing game, where the computer would generate a number and the user was prompted to guess. We were to create a method to play only one game, and then create a while loop in the main to make the game playable again. In the end, we need to show statistics. I'm having trouble with showing the "best game." That is a game where the amount of guesses is the least.
Here is the code:
import java.util.Random;
import java.util.Scanner;
public class GuessingGame {
public static final int MAX = 100;
// This is the main. Here we can see a do/while loop
// and a few variables that were created to compliment it.
public static void main(String[] args) {
Random rand = new Random();
Scanner console = new Scanner(System.in);
intro();
String s = "";
int totalGames = 0;
int totalGuess = 0;
do {
totalGuess = game(console);
System.out.print("Do you want to play again? ");
s = console.next();
totalGames++;
} while (s.equals("y") || s.equals("Y") || s.equals("Yes") ||
s.equals("yes") || s.equals("Yes"));
totalGuess = totalGuess;
statistics(totalGames, totalGuess);
}
// This method prints out the intro.
public static void intro() {
System.out.println("This program allows you to play a guessing
game.");
System.out.println("I will think of a number between 1 and");
System.out.println(MAX + " and will allow you to guess until");
System.out.println("you get it. For each guess, I will tell you");
System.out.println("whether the right answer is higher or lower");
System.out.println("than your guess.\n ");
}
// This method plays the game only once. It's later used in the main.
// Returns the
// number of guesses for one game.
public static int game(Scanner console) {
Random rand = new Random();
int random = rand.nextInt(MAX) + 1;
System.out.println("I'm thinking of a number between 1 and " + MAX + "
... (it's " + random + " )");
System.out.print("Your guess? > ");
int guess = console.nextInt();
int count = 0;
do {
if ((random - guess) > 0) {
System.out.println("It's higher.");
System.out.print("Your guess? > ");
guess = console.nextInt();
count++;
}
else if ((random - guess) < 0) {
System.out.println("It's lower.");
System.out.print("Your guess? > ");
guess = console.nextInt();
count++;
}
else if (random == guess) {
count++;
}
} while (random != guess);
if (count == 1) {
System.out.println("You got it right on the first guess!!");
}
else {
System.out.println("You got it right in " + count + " guesses.");
}
return count;
}
// This method prints out the statistics.
public static void statistics(int x, int y) {
System.out.println("total games = " + x);
System.out.println("total guesses = " + (y));
System.out.println("guesses/game = ");
System.out.println("best game = ");
}
}

Have a look when totalGuess is assigned:
public static void main(String[] args) {
Random rand = new Random();
Scanner console = new Scanner(System.in);
intro();
String s = "";
int totalGames = 0;
int totalGuess = 0;
// ^ Initialized to zero
do {
totalGuess = game(console);
// ^ Assigned (not added) to the return value from game.
// Did you mean: totalGuess += game(console); ?
System.out.print("Do you want to play again? ");
s = console.next();
totalGames++;
} while (s.equals("y") || s.equals("Y") || s.equals("Yes") ||
s.equals("yes") || s.equals("Yes"));
totalGuess = totalGuess;
// ^ Assigned to itself. No action.
statistics(totalGames, totalGuess);
}

Random two-digit number guessing game in Java

I'm working on a "game" for the user to guess a random two-digit number, and this is my "robust" version so far:
import static java.lang.System.*;
import java.util.*;
public class RandomNumberGuessing {
public static Scanner scan = new Scanner(in);
public static void main(String args[]){
Random generator = new Random ();
int Low = 10;
int High = 99;
int answer = generator.nextInt (High - Low) + Low;
int answerFirstDigit = Integer.parseInt(String.valueOf(answer).substring(0,1));
int answerSecondDigit = Integer.parseInt(String.valueOf(answer).substring(1,2));
int count = 0;
out.println ("Welcome to the two digit number guessing game!");
out.println ("We have randomly chosen a two-digit number");
out.println ("And you have to guess it after 5 tries!");
out.println ("Guess the number: ");
while (!scan.hasNextInt ()) {
scan.next ();
out.println ("You have to input a valid two-digit integer!");
}
int guess = scan.nextInt ();
while (guess != answer && count < 4){
count ++;
out.println("Wrong number! You have " + (5 - count) + " tries left:");
if (Integer.parseInt(String.valueOf(guess).substring(0,1)) == answerFirstDigit){
out.println("But you got the first digit correctly!");
} else if (Integer.parseInt(String.valueOf(guess).substring(1,2)) == answerSecondDigit){
out.println("But you got the second digit correctly!");
} else if (Integer.parseInt(String.valueOf(guess).substring(1,2)) == answerSecondDigit || Integer.parseInt(String.valueOf(guess).substring(0,1)) == answerSecondDigit){
out.println("One or two digits are correct but in the wrong place!");
}
while (!scan.hasNextInt ()) {
scan.next ();
out.println ("You have to input a valid two-digit integer!");
}
guess = scan.nextInt ();
}
if (guess == answer){
out.println("Congratulations! The number was " + answer + "!");
} else{
out.println("The number was " + answer + ". Better luck next time!");
}
}
}
But I'm having a problem with forcing the user to input a two-digit number only. I tried using:
while(guess < 10 || guess > 99){
scan.next();
out.println("Invalid number!");
guess = scan.nextInt();
}
I added that after the while loop to make sure the user entered an integer, and when I enter a 3 or 4-digit number in the console (I run the code on IntelliJ IDEA), it just seems to hang with no response. It doesn't even print out "Invalid number!" and just hangs. Do I have to rewrite the code using methods or are there any other things I can add to the existing code to make sure the user enters a TWO-DIGIT INTEGER? Thanks in advance

To check that the user enters just two digit numbers, i would use two methods to verify that.
Things to check:
User must enter something, i.e do not accept null or empty
Everything user enters must be exactly two characters long
When the characters are two, they have to all be digits
In your program you can do these
1. Get input as string
2. Call validString
3. If valid, then convert to integer
4. Check that number is between range (if the user entered 01, this evaluates to true). Integer.ParseInt could catch this but good to check anyway
Complete program should be something like this
import static java.lang.System.*;
import java.util.*;
public class RandomNumberGuessing {
public static Scanner scan = new Scanner(in);
public static void main(String args[]) {
final int tries = 5; // max number of tries
Random generator = new Random();
int Low = 10;
int High = 99;
int answer = generator.nextInt(High - Low) + Low;
int firstDigit = getFirst(answer);
int secondDigit = getSecond(answer);
out.println("Welcome to the two digit number guessing game!");
out.println("We have randomly chosen a two-digit number");
out.println("And you have to guess it after " + tries + " tries!");
int guess = 0; // number guessed
int count = 0; // number of failed guesses
do {
out.println("Guess the number: ");
String guessString = scan.nextLine(); // just read everything
// entered
if (validString(guessString)) {
guess = Integer.parseInt(guessString);
if (guess >= Low && guess <= High) { // check range and only
// process valid range
count++;
if (count == tries) {
out.print("Max guess reached.\nThe values were ");
out.println(firstDigit + " and " + secondDigit);
break;
}
out.println("You guessed " + guess);
// get the first and second digits
int first = getFirst(guess);
int second = getSecond(guess);
// compare them and process
if (guess == answer) {
out.println("Congratulations. You made the right guess after "
+ count + " tries");
} else if (first == firstDigit) {
out.println("Guessed the first number rightly");
} else if (second == secondDigit) {
out.println("Guessed the second number rightly");
} else {
out.print("No matching guess. You have ");
out.println((tries - count) + " guesses left");
}
} else {
out.println("Out of range!");
}
} else {
out.println("Bad Value.");
}
} while (guess != answer && count < tries);
}
// Validate an input Checks for length [2 characters] and that everything is
// a digit
private static boolean validString(final String guess) {
if (guess != null && !guess.isEmpty()) { // if not null and not empty
if (guess.length() == 2 && isAllDigits(guess)) { // length and digit
return true;
} else {
return false;
}
} else {
return false;
}
}
// Verify that all characters in a string are numbers
private static boolean isAllDigits(final String input) {
for (char c : input.toCharArray()) {
if (!Character.isDigit(c))
return false;
}
return true;
}
// get the first digit
private static int getFirst(final int value) {
return Integer.parseInt(String.valueOf(value).substring(0, 1));
}
// Get the second digit
private static int getSecond(final int value) {
return Integer.parseInt(String.valueOf(value).substring(0, 1));
}
}

ArrayList lottery game - excess array lists

I have been tinkering with this program for a while, but I still do not know what is wrong.
My problem is that if I want to get more than 1 ticket it gives me more array lists than expected. I cannot find a pattern as if I enter 2, I get 3, and if I enter 3, I get 6, and if I enter 4, I get back 10.
Input: Amount for how many tickets I want.
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;
public class ArrayListLottery {
public static void main(String[] args) {
int range = 49, amount = -1, number = 0, choice = -1;
// ArrayList<Integer> tickets = new ArrayList<Integer>();
ArrayList<ArrayList<Integer>> games = new ArrayList<ArrayList<Integer>>();
do {
System.out.println("Enter amount of lottery tickets you want");
Scanner in = new Scanner(System.in);
if (amount < 0) {
amount = in.nextInt();
}
while (amount != 0) {
System.out.println("Entered while block");
for (int i = 0; i < amount; i++) {
// Create an arraylist for how
// many tickets i want
ArrayList<Integer> tickets = new ArrayList<Integer>();
games.add(tickets);
for (int k = 0; k < 6; k++) { // Limit the size of a ticket to
// 6
if (tickets.size() < 6) {
number = (int) (range * Math.random()) + 1;
tickets.add(number);
Collections.sort(tickets);
} else {
break;
}
}// limit for loop to 6 end
}// arraylist creator end
amount--;
System.out.println("Amount is " + amount);
}//while loop end
for (List<Integer> i : games) { //print out each ticket
for (Integer n : i) {
System.out.print(n + " ");
}
System.out.println();
} //print out for-loop end
games.clear();
System.out.println("Type 0 to exit, otherwise pick any other number ");
choice = in.nextInt();
amount = choice;
} while (amount != 0);
System.out.println("Good luck!");
}
}

Fibonacci number of amount will be your size of games list.
It is happening because you have applied while as well as for loop for amount.
Replace your while loop with if statement.

You can put
amount--;
in the for loop which generate the arraylist.
Like this:
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;
public class ArrayListLottery {
public static void main(String[] args) {
int range = 49, amount = -1, number = 0, choice = -1;
// ArrayList<Integer> tickets = new ArrayList<Integer>();
ArrayList<ArrayList<Integer>> games = new ArrayList<ArrayList<Integer>>();
do {
System.out.println("Enter amount of lottery tickets you want");
Scanner in = new Scanner(System.in);
if (amount < 0) {
amount = in.nextInt();
}
while (amount != 0) {
System.out.println("Entered while block");
for (int i = 0; i < amount; i++) {
// Create an arraylist for how
// many tickets i want
ArrayList<Integer> tickets = new ArrayList<Integer>();
games.add(tickets);
for (int k = 0; k < 6; k++) { // Limit the size of a ticket to
// 6
if (tickets.size() < 6) {
number = (int) (range * Math.random()) + 1;
tickets.add(number);
Collections.sort(tickets);
} else {
break;
}
}// limit for loop to 6 end
amount--;
}// arraylist creator end
System.out.println("Amount is " + amount);
}//while loop end
for (List<Integer> i : games) { //print out each ticket
for (Integer n : i) {
System.out.print(n + " ");
}
System.out.println();
} //print out for-loop end
games.clear();
System.out.println("Type 0 to exit, otherwise pick any other number ");
choice = in.nextInt();
amount = choice;
} while (amount != 0);
System.out.println("Good luck!");
}
}
Besides that, you can add a breakpoint to step over your program line by line which may make you find the bug quickly.

Using a do-while to restart a game in java

Please help with the swtich case need for a game
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("Please Enter a number");
int day = input.nextInt();
switch(day)
{
case 1: System.out.println("1 Microphone");
break;
case 2: System.out.println("2 Loud Speakers 1 Microphone ");
break;
case 3: System.out.println("3 Keyboards 2 Loudspeakers 1 Microphone ");
break;
case 4: System.out.println("4 Java Books 3 Keyboards 2 Loudspeakers 1 Microphone");
break;
case 5: System.out.println("5 Iphones 4 Java Books 3 Keyboards 2 Loudspeakers 1 Microphone");
break;
default: System.out.println("Enter A Valid Prize Day");
}
}

As #AlexandreSantos pointed out, you need to reinitialise the values of maxRolls and sum every time you restart the game. That is, these initialisations should be the first things executed in your do {} while () loop.
do {
int maxRolls = 7;
int sum = 0;
// ...
} while (option);
I'd also give you other recommendations:
in Java, the class names, by convention, start with an upper-case letter. Thus, I'd name your class Game instead of game.
The following code (and its equivalent with "no"):
(userInputTwo.equals("Yes") || userInputTwo.equals("yes") || userInputTwo.equals("YES"))
... can be replaced by:
userInputTwo.equalsIgnoreCase("yes")
... since, as you mentioned in your question, you're actually simply trying to ignore the case ;)
You're doing all that asking the user whether is wants to restart or not in two places. You could (should) actually simply do it once, after having printed either "You won" or "You lost".
I'd suggest to replace:
if (sum >= 43) {
System.out.println("You Win");
System.out.print("Would You Like To Play Again . Yes or No?");
final String userInput = input.nextLine();
if (userInput.equals("Yes") || userInput.equals("yes") || userInput.equals("YES")) {
// MISSING CODE TO RESTART THE PROGRAM
option = true;
} else if (userInput.equals("No") || userInput.equals("no") || userInput.equals("NO")) {
System.exit(0);
}
}
if (sum < 43 || sum % 10 == 0) {
System.out.println("You Lose");
System.out.print("Would You Like To Play Again . Yes or No?");
final String userInputTwo = input.nextLine();
if (userInputTwo.equals("Yes") || userInputTwo.equals("yes") || userInputTwo.equals("YES")) {
option = true;
// MISSING CODE TO RESTART THE PROGRAM
} else if (userInputTwo.equals("No") || userInputTwo.equals("no") || userInputTwo.equals("NO")) {
System.exit(0);
}
}
... by:
if (sum >= 43) {
System.out.println("You Win");
}
if (sum < 43 || sum % 10 == 0) {
System.out.println("You Lose");
}
System.out.print("Would You Like To Play Again . Yes or No?");
final String userInput = input.nextLine();
if ("yes".equalsIgnoreCase(userInput) {
// MISSING CODE TO RESTART THE PROGRAM
option = true;
} else if ("no".equalsIgnoreCase(userInput)) {
System.exit(0);
}
... or, even better, extracting this into an other method.
Or, even better, not even checking for one of the possibilities and make it the default one, in case the user enters something that's neither "yes" nor "no":
private static boolean restart(final Scanner input) {
// I choose to interpret any input that's different from "yes" as a "no".
System.out.print("Would You Like To Play Again. Yes or No? (default: No)");
final String userInput = input.nextLine();
if ("yes".equalsIgnoreCase(userInput)) {
return true;
}
return false;
}
... which can obviously then become:
private static boolean restart(final Scanner input) {
// I choose to interpret any input that's different from "yes" as a "no".
System.out.print("Would you like to play again? [Yes/No] (default: No)");
return "yes".equalsIgnoreCase(input.nextLine());
}
... and the option variable could disappear:
do {
...
} while (Game.restart(input));
You could (should) use Random instead of Math.random(), it's just way more convenient.
For example:
final int dieOne = (int) (Math.random() * faces) + 1;
final int dieTwo = (int) (Math.random() * faces) + 1;
final int totalRollForRound = dieOne + dieTwo;
... could become:
// Outside of the do {} while ():
final Random r = new Random();
// Inside the do {} while ():
final int totalRollForRound = r.nextInt(faces) + r.nextInt(faces) + 2;
You should always close the Scanner before leaving the program.
Use the try-with-resources syntax:
private static boolean restart() {
try (final Scanner input = new Scanner(System.in) {
// I choose to interpret any input that's different from "yes" as a "no".
System.out.print("Would you like to play again? [Yes/No] (default: No)");
return "yes".equalsIgnoreCase(input.nextLine());
}
}
One last thing: your sum % 10 == 0 is weird: you've already told the user that he won if he scored at least 43, and he's gonna lose if he scored less than 43... You should either:
Test that condition before checking whether the user has scored more than 43 (and therefore also rejecting scores like 50, 60, 70, 80...)
... or:
Forget about that rule that only aims to reject 10, 20, 30 and 40, which are already covered by the score < 43 rule.
Cheers ;)
Just 'cause I felt bored, I actually applied my own advices (and a few more) to your code:
import java.util.Random;
import java.util.Scanner;
public class Game {
private static final int FACES = 6;
private static final int MAX_ROLLS = 7;
private static final Random R = new Random();
public static void main(final String[] args) {
try (final Scanner input = new Scanner(System.in)) {
do {
if (Game.roll() >= 43) {
System.out.println("You won!");
} else {
System.out.println("You lost.");
}
} while (Game.restart(input));
}
}
private static int roll() {
int maxRolls = MAX_ROLLS;
int sum = 0;
for (int i = 1; i < maxRolls; i++) {
final int dieOne = R.nextInt(FACES) + 1;
final int dieTwo = R.nextInt(FACES) + 1;
sum += dieOne + dieTwo;
System.out.println("Roll #" + i + ": You rolled " + dieOne + " and " + dieTwo + ".\tYour new total is: " + sum);
if (dieOne == dieTwo) {
System.out.println("DOUBLES! You get an extra roll.");
maxRolls++;
}
}
return sum;
}
private static boolean restart(final Scanner input) {
System.out.print("Play again? [Yes/No] (default: No): ");
return "yes".equalsIgnoreCase(input.nextLine());
}
}

Sounds like you want an outer loop; each time through the loop the user plays one game. At the top of that loop, you initialize the values that you need to play one game:
boolean playingMoreGames = false;
do
{
int sum = 0;
int maxRolls = 6;
int rollsMade = 0;
boolean gameOver = false;
do
{
// roll dice
// determine win or loss
// and determine whether game is over
// include testing rollsMade against maxRolls
}
while (!gameOver)
// ask user whether he wants to play again and set playingMoreGames accordingly
}
while (playingMoreGames);
I have suggested a change to a while loop that executes as long as the maxRolls has not been reached. It is not a good idea to modify the target of a for loop within the loop; in some languages, at least, the behavior is undefined, and it confuses the reader. Since maxRolls can change, you need a different looping form there.
And you don't really need to call System.exit(); if you "fall out of" the bottom of your main routine, your program will just exit since it has no more instructions to execute.
I don't recommend do while(true) in this case; the (small) problem with it is that it makes it harder for the reader to determine when the loop exits. Not a big deal.
Good luck.