Develop Reference

Java Slot machine college project

I'm making a slot machine for a college project. There are loads and loads of similar projects talked about online however the requirements for my project are slightly different. Here is my task:
The player starts with £1 credit, with each go costing 20 p.
If the Fruit Machine “rolls” two of the same symbol, the user wins 50 p.
The player wins £1 for three of the same and £5 for 3 Bells.
The player loses £1 if two skulls are rolled and all of his/her money if three skulls are rolled.
The player can choose to quit with the winnings after each roll or keep playing until there is no money left.
What I've come up with so far is this:
for ( int runCount = 1; runCount <= 3; runCount ++ ) {
int symIndex = r.nextInt(6);
if (symIndex == 0) {
symbol = "cherry";
} else if (symIndex == 1){
symbol = "orange";
} else if (symIndex == 2){
symbol = "lemon";
} else if (symIndex == 3){
symbol = "bell";
} else if (symIndex == 4){
symbol = "star";
} else if (symIndex == 5){
symbol = "skull";
}
if (runCount == 1){
reel1 = symbol;
} else if ( runCount == 2 ){
reel2 = symbol;
} else if ( runCount == 3 ){
reel3 = symbol;
}
}
System.out.println(reel1 + " " + reel2 + " " + reel3);
Which is great and spits out 3 random symbols but what is I need is a way is for it to somehow treat the bell and skull symbols differently. There must be an easier way than write out every possible combination in an if statement. In all the other projects I've seen the prize if statements have looked something like this
if (reel1 == reel2 && reel1 == reel3 && reel2 == reel3)
System.out.println("You have won!");
Or something about that etc etc. But if I do it this way it's not defining the actual symbol but just storing it in one of the reel variables so I can't make if statements for those specific outcomes.
Any help would be greatly, greatly appreciated. Even if you could just tell me how to phrase my question properly so I could search it would be helpful

I've changed things a little. Rather than storing 3 unique fields reel1, reel2 and reel3 you can re-use the counter variable you're using to control the for-loop to place the chosen symbols into an array. Note: you need to start the counter at 0, but this makes little/no difference.
private static final String CHERRY = "cherry";
private static final String ORANGE = "orange";
private static final String LEMON = "lemon";
private static final String BELL = "bell";
private static final String STAR = "star";
private static final String SKULL = "skull";
private static final Random random = new Random();
public static void main(String[] args) {
String[] symbols = new String[3];
pickRandomSymbolsForReels(symbols);
displayReels(symbols);
Map<String, Integer> symbolCounts = new HashMap<>();
checkResults(symbols, symbolCounts);
displayResults(symbolCounts);
}
private static void checkResults(String[] symbols, Map<String, Integer> symbolCounts) {
// for each symbol
// if (symbolCounts.get(symbol) != null) {
// symbolCounts.put(symbol, 1);
// } else {
// int incrementedValue = symbolCounts.get(symbol) + 1;
// symbolCounts.put(symbol, incrementedValue);
// }
}
private static String[] pickRandomSymbolsForReels(String[] symbols) {
for (int reelIndex = 0; reelIndex < symbols.length; reelIndex++) {
int choice = random.nextInt(6);
switch (choice) {
case 0:
symbols[reelIndex] = CHERRY;
break;
case 1:
symbols[reelIndex] = ORANGE;
break;
case 2:
symbols[reelIndex] = LEMON;
break;
case 3:
symbols[reelIndex] = BELL;
break;
case 4:
symbols[reelIndex] = STAR;
break;
case 5:
symbols[reelIndex] = SKULL;
break;
}
}
return symbols;
}
private static void displayReels(String[] symbols) {
for (String symbol : symbols) {
System.out.print(symbol + " ");
}
System.out.println();
}
private static void displayResults(Map<String, Integer> symbolCounts) {
/**
* Here you'll need to understand the logic of various events.
* e.g
* 3 skulls - instantly lose all credit - game over
* 2 skulls - decreaseBalance(1.00)
* 3 Bells - increaseBalance(amount)
* 3 of any other symbol - increaseBalance(amount)
* 2 of any thing else - increaseBalance(amount)
* .. etc
*/
// if (hasThreeSkulls(symbolCounts.get(SKULL)) {
// gameOver();
// } else if (hasTwoSkulls(symbolCounts.get(SKULL)) {
// decreaseBalance(100) // note when working with money, store pence amount only and display the value as pounds and pence.. otherwise you'll have issues
// } etc ..
}
Next gather the stats from the reels (counts of the symbols of interest). Finally check the stats for winning/losing results. This will be a bunch of if, else-if statements.

Okay so I'm coding a roll the dice game on java

This is the code I have, but I want it to be able to roll the dice based on the number of trials the user inputs and then display the frequencies of each face.
This code isn't working as I would expect.
Also I would like to change the switch cases to if and else if statements, if anybody could help me out with that would be amazing, I've been working on this for a while now.
import java.util.Random;
import java.util.Scanner;
public class DieRoll {
public static void main(String[] args) {
// TODO Auto-generated method stub
Random randomNumbers = new Random();
int one=0;
int two=0;
int three=0;
int four=0;
int five=0;
int six=0;
int trials;
int face;
System.out.println("Please enter the number of trials");
Scanner scan= new Scanner (System.in);
trials= scan.nextInt();
for(int rolls= 1; rolls==trials; rolls++);{
face= randomNumbers.nextInt(6) + 1;
// determine roll value 1-6 and increment appropriate counter
switch ( face )
{
case 1:
++one; // increment the 1s counter
break;
case 2:
++two; // increment the 2s counter
break;
case 3:
++three; // increment the 3s counter
break;
case 4:
++four; // increment the 4s counter
break;
case 5:
++five; // increment the 5s counter
break;
case 6:
++six; // increment the 6s counter
break; // optional at end of switch
}
}
System.out.println( "Face\tFrequency" ); // output headers
System.out.printf( "1\t%d\n2\t%d\n3\t%d\n4\t%d\n5\t%d\n6\t%d\n",
one, two, three, four,
five, six );
scan.close();
}
}

In your for loop:
Remove the semicolon (;) just after the for(int rolls= 1; rolls==trials; rolls++) line.
Change:
for(int rolls= 1; rolls==trials; rolls++)
to:
for(int rolls= 1; rolls<=trials; rolls++)
As far as changing switch to if-else-if, not sure why you would want to do this, but simply write it as:
if(face == 1){
one++;
}
else if(face ==2){
two++;
}
and so on..

Please have a look at this:
public class Main {
private static final Random RANDOM_NUMBER_GENERATOR = new Random();
public static void main(String[] args) {
int numberOfTrials;
int[] facesFrequencies = new int[6];
System.out.println("Please enter the number of trials");
Scanner scanner = new Scanner(System.in);
numberOfTrials = scanner.nextInt();
scanner.close();
for (int numberOfRolls = 1; numberOfRolls <= numberOfTrials; numberOfRolls++) {
int face = rollDice();
if (face == 1) {
facesFrequencies[0] += 1;
} else if (face == 2) {
facesFrequencies[1] += 1;
} else if (face == 3) {
facesFrequencies[2] += 1;
} else if (face == 4) {
facesFrequencies[3] += 1;
} else if (face == 5) {
facesFrequencies[4] += 1;
} else if (face == 6) {
facesFrequencies[5] += 1;
}
}
System.out.println("Face\tFrequency");
for (int i = 0; i < facesFrequencies.length; i++) {
System.out.printf("%d\t\t%d%n", i, facesFrequencies[i]);
}
}
private static int rollDice() {
return RANDOM_NUMBER_GENERATOR.nextInt(6) + 1;
}
}
I've put the results (int one to int six) into an array. facesFrequencies[0] will be the same as int one.
The ; after for (...) is syntactically incorrect.
Switch statement is replaced with if statement.

How to validate the selection menu using a loop

Can someone edit my code to make it loop the selection menu. If the choice is not one of the 5 options it will prompt the user to re-enter until it is a valid option. If possible an explanation would be helpful as well. Thanks
Here is my code.
import java.util.*;
public class ShapeLoopValidation
{
public static void main (String [] args)
{
chooseShape();
}
public static void chooseShape()
{
while (true){
Scanner sc = new Scanner(System.in);
System.out.println("Select a shape number to calculate area of that shape!");
System.out.print("Circle = 1. \nRectangle = 2. \nTriangle = 3. \nExit = 4. \nINPUT : ");
int shapeChoice = sc.nextInt();
//while (true) {
if (shapeChoice >= 1 && shapeChoice <=4)
{
if (shapeChoice == 1)
{
circle();
}
else if (shapeChoice == 2)
{
rectangle();
}
else if (shapeChoice == 3)
{
triangle();
}
else if (shapeChoice == 4)
{
return;
}
}
else
{
System.out.print("Error : Choice " + shapeChoice + "Does not exist.");
}
}
class Test {
int a, b;
Test(int a, int b) {
this.a = a;
this.b = b;
}
}
}

First: take a look at switch
Second: read a bit about do-while loops (they are usually a good fit for this kind of situations).
Now, how I would implement it (but you should really learn how to make a loop in this scenarios):
public static void chooseShape () {
boolean valid = false;
do {
Scanner sc = new Scanner(System.in);
System.out.println("Select a shape number to calculate area of that shape!");
System.out.print("Circle = 1. \nRectangle = 2. \nTriangle = 3. \nExit = 4. \nINPUT : ");
int shapeChoice = sc.nextInt();
switch (shapeChoice) {
valid = true;
case 1:
circle();
break;
case 2:
rectangle();
break;
case 3:
triangle();
break;
case 4:
return;
default:
valid = false;
System.out.println("Error : Choice " + shapeChoice + "Does not exist.");
System.out.println("Please select one that exists.")
}
} while (!valid)
}

Use do-while flow control until EXIT code entered:
int shapeChoice;
do {
System.out.println("Select a shape number to calculate area of that shape!");
System.out.print("Circle = 1. \nRectangle = 2. \nTriangle = 3. \nExit = 4. \nINPUT : ");
int shapeChoice = sc.nextInt();
// then use if-else or switch
} while (shapeChoice != 4);
OR
use break statement to loop break at your code as bellow:
else if (shapeChoice == 4)
{
break;
}

Java - How to contain a switch statement menu in a while loop

I have a main menu class which gets a choice from the user and then uses that choice to select other classes from a switch statement pertaining to the menu options. My code is:
public static void main(String[] args) {
int dieOne = 0;
int dieTwo = 0;
int choice = 0;
DiceMaker dice = new DiceMaker(); // class that creates the dice
RollDice roll = new RollDice(); // class that imitates roll
DiceMenu menu = new DiceMenu();
DiceRoller series = new DiceRoller();
System.out.println("Welcome to the Dice Roll Stats Calculator!\n");
while (choice != 4) {
menu.DiceMenu();
choice = menu.getUserChoice();
switch (choice) {
case 1:
dice.diceMaker();
dieOne = dice.DieOne();
dieTwo = dice.DieTwo();
System.out.println(dice.DieOne() + dice.DieTwo());
return;
case 2:
roll.rollDice(dieOne, dieTwo);
roll.displayRoll();
return;
case 3:
series.diceRoller();
series.displayResults();
return;
case 4:
break;
}// switch (choice)
} // while (choice != 4)
}
Case for is the 'Exit' option, so I put the switch statement in a while loop with the boolean condition being not equal to 4 so that when the choice was set to 4 the loop would stop. The proper case executes but the problem I'm having is that the loop, and consequently the program stop after each case that I try, even if the choice was not 4. I tried using break statements after case 1, 2 and 3 as well, and when I did that, it would just repeat the case in an infinite loop. I tried to figure this out on my own cut could never find anything that resembled what I was seeing enough for me to figure out what the problem was. I'm guessing this probably isn't the best way to make a menu in the future. Thank in advance.
The rest of my code is as follows. Please note, DiceRoller class is still under construction, but DiceMaker and RollDice classes seem to be working.
DiceMenu class:
public class DiceMenu
{
public static final int CHOICE_UNKNOWN = 0;
public static final int CHOICE_MAKE_DICE = 1;
public static final int CHOICE_ROLL_ONCE = 2;
public static final int CHOICE_SERIES_ROLL = 3;
public static final int CHOICE_QUIT = 4;
private int choice = 0;
Scanner scan = new Scanner(System.in);
public int DiceMenu()
{
while ( this.choice < 1 || this.choice > 4 ) // while loop keeps choices in range
{
System.out.println(" MAIN MENU\n");
System.out.println("1. Create Your Dice");
System.out.println("2. Roll Your Dice");
System.out.println("3. Perform A Series Of Rolls And Show Stats");
System.out.println("4. Exit\n");
try // avoid invalid input
{
System.out.print("Please choose an option: ");
this.choice = scan.nextInt(); // get number of sides from user
}
catch (InputMismatchException e)
{
//if input is invalid, returns to beginning of loop
System.out.println("Invalid Input. Please try again.\n");
scan.next();
continue;
}
if ( this.choice < 1 || this.choice > 4 ) // if input is out of range
// notify user before continuing
{
System.out.println("Choice must reflect menu options. (1-4)"
+ " Please try again.\n");
this.choice = 0;
}
}//while ( this.choice < 1 || this.choice > 4 )
return 0;
}
public int getUserChoice()
{
return this.choice;
}
}
RollDice class:
public class RollDice
{
private int roll;
private int rollOne;
private int rollTwo;
private int rollTotal;
public int rollDice (int dieOne, int dieTwo)
{
this.rollOne = 1 + (int)(Math.random() * dieOne);
this.rollTwo = 1 + (int)(Math.random() * dieTwo);
this.rollTotal = this.rollOne + this.rollTwo;
return 0;
}
public void displayRoll()
{
System.out.println("You roll a " + rollOne + " and a "
+ rollTwo + " for a total of " +
rollTotal + "!"); //display separate and total
//roll amounts
if ( rollTotal == 2 ) // if/else tests for special rolls
{
System.out.println("Snake Eyes!");
}
else if ( rollTotal == 7 )
{
System.out.println("Craps!");
}
else if ( rollOne == 6 && rollTwo == 6 )
{
System.out.println("Boxcars!");
}
}
}// public class DiceRoller
DiceMaker class:
public class DiceMaker
{
private int sides = 0;
private int dieOne;
private int dieTwo;
public int diceMaker()
{
while ( sides < 4 || sides > 20 ) // while loop keeps sides within range
{
Scanner scan = new Scanner(System.in);
try // avoid invalid input
{
System.out.print("Please enter the number of sides each die "
+ "should have (must be between 4 and 20): ");
this.sides = scan.nextInt(); // get number of sides from user
}
catch (InputMismatchException e)
{
//if input is invalid, returns to beginning of loop
System.out.println("Invalid Input. Please try again.\n");
scan.next();
continue;
}
if (sides < 4 || sides > 20) // if input is out of range
// notify user before continuing
{
System.out.println("Die must have between 4 and 20 sides."
+ " Please try again.\n");
}
}//while ( sides < 4 || sides > 20 )
this.dieOne = sides;
this.dieTwo = sides;
return 0;
}
public int DieOne()
{
return this.dieOne;
}
public int DieTwo()
{
return this.dieTwo;
}
}// public class DiceMaker

Remove the return(s) from cases 1,2 and 3. If you return from main the program terminates. You want to loop so don't do that. However, as pointed out by #ajb in the comments below, you don't want the case(s) to fall through. So you need break(s).
case 1: dice.diceMaker();
dieOne = dice.DieOne();
dieTwo = dice.DieTwo();
System.out.println(dieOne + dieTwo);
// return;
break; // <-- applies to innermost block (switch).
case 2: roll.rollDice(dieOne, dieTwo);
roll.displayRoll();
// return;
break; // <-- applies to innermost block (switch).
case 3: series.diceRoller();
series.displayResults();
// return;
break; // <-- applies to innermost block (switch).
Also, you could use continue (here, which would apply to the innermost loop). Finally, remember that case 4 terminates the loop (because choice is 4) and you don't need case 4 for that reason.

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.