Develop Reference

I cant figure out to implement -1 as a sentinel value using a while loop.

I can't figure out to implement -1 as a sentinel value using a while loop. Note that the program needs to be running all times except when the users enter the value -1 it should stop. Technically the program should stop at any time when the user enters the sentinal value(-1).
import java.util.Scanner;
import java.util.Random;
public class Multi {
public static void main(String[] args) {
Random rand = new Random();
Scanner scan = new Scanner(System.in);
int randomOne, randomTwo, product, userInput;
while(true) {
randomOne = Math.abs(rand.nextInt()%10);
randomTwo = Math.abs(rand.nextInt()%10);
product = randomOne * randomTwo;
System.out.println("How much is " + randomOne + " times " + randomTwo
+ "?");
userInput = scan.nextInt();
if (product == userInput) {
System.out.println("Very Good!");
}
else {
while (product != userInput) {
System.out.println("No. Please try again.");
System.out.println("How much is " + randomOne + " times " +
randomTwo + "?");
userInput = scan.nextInt();
if (product == userInput) {
System.out.println("Very Good!");
}
}}
}
}
}
So at all times when we ask input from the user, if they enter -1 the program should stop.

You could check if the value is -1 upon every iteration and then write a break statement, but below is a slightly cleaner implementation.
import java.util.Scanner;
import java.util.Random;
public class Multi {
public static void main(String[] args) {
Random rand = new Random();
Scanner scan = new Scanner(System.in);
int randomOne, randomTwo, product, userInput;
boolean playingGame = true;
while (playingGame) {
randomOne = Math.abs(rand.nextInt() % 10);
randomTwo = Math.abs(rand.nextInt() % 10);
product = randomOne * randomTwo;
System.out.println("How much is " + randomOne + " times " + randomTwo + "?");
userInput = scan.nextInt();
while (userInput != -1 && product != userInput) {
System.out.println("No. Please try again.");
System.out.println("How much is " + randomOne + " times " +
randomTwo + "?");
userInput = scan.nextInt();
}
if (product == userInput) {
System.out.println("Very Good!");
} else {
playingGame = false;
}
}
scan.close();
}
}

In this java code how can i print out correctly the names array in the overview?

My only question is in the overview part how can I print out the trailers rental name correctly? like this:
sample
But my overview code not exactly working as I want. What is the problem?
(I understand the counting in an array starting from zero)
import java.util.Scanner;
public class TrailerRental {
Scanner kb=new Scanner(System.in);
int weightSmall=750;
int weightLarge=3000;
int smallTrailerCounter =0;
int largeTrailerCounter =0;
String smallClientName;
String largeClientName;
String [] smallTrailersClients=new String[5];
String [] largeTrailersClients= new String[3];
public static void main(String[] args) {
new TrailerRental().run();
}
public void run(){
menu();
int menu=kb.nextInt();
while (menu==1 || menu==2|| menu==3){
if(menu==1){
smallTrailer();
}
if (menu==2){
largeTrailer();
}
if (menu==3){
overView();
}
}
if (menu==9){
System.out.println("Goodbye!");
}
else {
System.out.println("Error, incorrect input try again!");
System.out.println();
run();
}
}
public void overView() {
System.out.println("Overview");
System.out.println();
System.out.println("Rented Small trailers");
int notUsedSmallTrailer=5-smallTrailerCounter;
for (int i=0;i<smallTrailerCounter;i++){
System.out.println("Small trailer " +(i+1) + " :" +smallTrailersClients[i] );
}
System.out.println("There are "+notUsedSmallTrailer+ " out of 5 small trailers still available.");
System.out.println("Rented Large trailers");
int notUsedLargeTrailer=3-largeTrailerCounter;
for(int i=0;i<smallTrailerCounter;i++){
System.out.println("Large trailer " + (i+1) +" : "+largeTrailersClients[i] );
}
System.out.println("There are "+notUsedLargeTrailer+ " out of 3 large trailer still available ");
run();
}
public void largeTrailer() {
if (largeTrailerCounter>=3){
System.out.println("Unfortunately all Small trailers are out");
System.out.println("Would you like to rent a Small trailer instead?(y/n)");
String answer=kb.next();
if (answer.equals("y")){
smallTrailer();
}
if (answer.equals("n")){
run();
}
else {
System.out.println("Incorrect input, return to main menu");
run();
}
} else {
System.out.println("What is your name?");
largeClientName=kb.next();
System.out.println("Is the driver in possession of an E-type drivers license (y/n)?");
String answer=kb.next();
if (answer.equals("n")){
System.out.println("Unfortunately, a large trailer cannot be rented without a E-type drivers license. ");
run();
}
if (answer.equals("y")){
System.out.println("What is the weight of the load (in kg)?");
int weight=kb.nextInt();
if (weight<=weightLarge){
largeTrailerCounter++;
largeTrailersClients[largeTrailerCounter]=largeClientName;
run();
}
if (weight>weightLarge){
int difference=weight-weightLarge;
System.out.println("Warning! the maximum load "+weightLarge+" kg is exceeded by " +difference+ "kg" );
System.out.println("Are you sure you want to rent a trailer?(y/n)?");
String answer2=kb.next();
if (answer2.equals("n")){
run();
}
if (answer2.equals("y")){
largeTrailerCounter++;
largeTrailersClients[largeTrailerCounter]=largeClientName;
run();
}
else {
System.out.println("incorrect input,return to menu");
run();
}
}
}
}
}
public void smallTrailer() {
if (smallTrailerCounter>=5) {
System.out.println("Unfortunately all Small trailers are out");
run();
} else {
System.out.println("What is the customer last name?");
smallClientName = kb.next();
System.out.println("What is the weight of the load (in kg) ?");
int weight = kb.nextInt();
if (weight<=weightSmall){
smallTrailerCounter++;
smallTrailersClients[smallTrailerCounter]=smallClientName;
run();
}
if (weight > weightSmall) {
int difference = weight - weightSmall;
System.out.println("Warning the maximum load " + weightSmall + " kg is exceeded by " + difference + " kg!");
System.out.print("Are you sure you want to rent the small trailer? (y/n)");
String answer = kb.next();
if (answer.equals("n")) {
run();
}
if (answer.equals("y")) {
smallTrailerCounter++;
smallTrailersClients[smallTrailerCounter]=smallClientName;
run();
}
while (answer != "y" || answer != "n") {
System.out.print("Are you sure you want to rent the small trailer? (y/n)");
answer = kb.next();
if (answer.equals("n")) {
run();
}
if (answer.equals("y")) {
run();
}
}
}
}
}
public void menu() {
System.out.println("***********************");
System.out.println("* Trailer rental ");
System.out.println("***********************");
System.out.println("* 1) Rent small trailer");
System.out.println("* 2) Rent large trailer");
System.out.println("* 3) Overview ");
System.out.println("* 9) Exit ");
System.out.println("***********************");
System.out.print("Select an option:");
}
}

You didn't add 1 to your smallTrailersClients[i] or largeTrailersClients[i]. You are referencing i + 1 in your for loop. The same will be needed to reference the correct name associated. Try this instead:
public void overView() {
System.out.println("Overview");
System.out.println();
System.out.println("Rented Small trailers");
int notUsedSmallTrailer=5-smallTrailerCounter;
for (int i=0;i<smallTrailerCounter;i++){
System.out.println("Small trailer " +(i+1) + " :" +smallTrailersClients[i+1] );
}
System.out.println("There are "+notUsedSmallTrailer+ " out of 5 small trailers still available.");
System.out.println("Rented Large trailers");
int notUsedLargeTrailer=3-largeTrailerCounter;
for(int i=0;i<smallTrailerCounter;i++){
System.out.println("Large trailer " + (i+1) +" : "+largeTrailersClients[i+1] );
}
System.out.println("There are "+notUsedLargeTrailer+ " out of 3 large trailer still available ");
run();
}

for each loop printing details from an arrayList using toString

I have been asked to :
 Create an EntertainmentRobot object and a HumanStudyRobot object (using the data previously
given) and store these objects in an array list.
 Set the purpose of each robot in the array using the data previously outlined in this paper.
 Print the details of each robot using the toString method.
I have did this and my code is below. But when I run the code, The details of each robot added to my arrayList are printed twice each. Any idea how I can fix it so that the details of each robot object in the array list only prints once? many thanks
package Program;
import java.util.ArrayList;
import java.util.Scanner;
public class Tester04 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
ArrayList<Robot> Robots = new ArrayList<Robot>();
HumanStudyRobot HumanStudyRobot1 = new HumanStudyRobot("HRP", 1.5, 58.0, "Kawada Industries");
HumanStudyRobot1.setPurpose("Study into human movement and perform a wide range of tasks.");
EntertainmentRobot EntertainmentRobot1 = new EntertainmentRobot("QRIO", 0.6, 7.3, "SONY");
EntertainmentRobot1.setPurpose("To live with you, make life fun and make you happy.");
Robots.add(EntertainmentRobot1);
Robots.add(HumanStudyRobot1);
for (Robot eachRobot : Robots) { //for loop to go through the array list
System.out.println(Robots.toString());
System.out.println("\n");
}
startRobot(Robots, input);
}
public static void startRobot(ArrayList<Robot> Robots, Scanner input){
for( int i = 0 ; i < Robots.size(); i++ ) {
Robots.get(i).start();
Robots.get(i).doTask();
Robots.get(i).doTask(input);
Robots.get(i).stop();
}
}
}
package Program;
import java.util.Scanner;
import org.omg.Messaging.SyncScopeHelper;
public class EntertainmentRobot extends Robot {
//constructor
public EntertainmentRobot(String name, double height, double weight, String manufacturer) {
super(name, height, weight, manufacturer);
this.energy = 10.0;
this.EnergyUnitsRequired = 0.75;
}
#Override
public void start() {
System.out.println("This is an Entertainment Robot. \nThe robot has started entertaining.");
}
#Override
public void stop() {
System.out.println("I have stopped entertaining people.");
System.out.println("--------------------------------------------------");
}
#Override
public void doTask(Scanner input) {
play();
talk();
walk();
}
#Override
public void doTask() {
// TODO Auto-generated method stub
}
public void talk() {
Scanner input = new Scanner(System.in);
System.out.println("Please enter a phrase for me to repeat");
String phrase = input.nextLine();
System.out.println("You have asked me to say the following phrase : " + phrase);
}
public void walk() {
Scanner input = new Scanner (System.in);
System.out.println("Would you like me to walk for you?");
if (input.nextLine().equalsIgnoreCase("Y")) {
System.out.println("For how many paces? ");
int steps = input.nextInt();
input.nextLine();
System.out.println("Which direction do you want me to walk? (Enter a number between 1 and 4.) ");
System.out.println("1 - " + Directions.FORWARD);
System.out.println("2 - " + Directions.BACKWARD);
System.out.println("3 - " + Directions.LEFT);
System.out.println("4 - " + Directions.RIGHT);
int selection = input.nextInt();
if (selection == 1 ) {
setDirection(Directions.FORWARD);
} else
if (selection == 2 ) {
setDirection(Directions.BACKWARD);
} else
if (selection == 3 ) {
setDirection(Directions.LEFT);
} else
if
(selection == 4 ) {
setDirection(Directions.RIGHT);
}
//output
System.out.println("I have walked " + getDirection() + " " + steps + " steps.");
}
else if (input.nextLine().equalsIgnoreCase("N")) {
System.out.println("Exitting the system.");
System.exit(0);
}
}
public void play () {
Scanner input = new Scanner(System.in);
boolean valid = false;
int selection;
do {
System.out.println("How many times would you like to play?");
while (!input.hasNextInt()) {
System.out.println("That is not a number");
input.nextLine();
}
selection = input.nextInt();
valid = true;
} while(!valid);
for (int i = 1; i < selection + 1; i ++ ) {
if (getEnergy() >= energyRequired()) {
energyConsumption();
} else if (getEnergy() < energyRequired()) {
System.out.println("------------WHOOPS--------------.");
System.out.println("I do not have enough energy to play.");
regenerate();
}
}
//input.close();
}
public String toString() {
return "---------------------------------\nI AM AN ENTERTAINMENT ROBOT \nThe details of the entertainment robot are below: \n" +
"Name : " + getName() + "\nWeight: " + getWeight() + "\nHeight: " + getHeight() + "\nManufacturer: " +
getManufacturer() + "\nPurpose: " + getPurpose() + "\n----------------------------";
}
}
package Program;
import java.util.Scanner;
public class HumanStudyRobot extends Robot {
//instance variables
public HumanStudyRobot(String name, double height, double weight, String manufacturer) {
super(name, height, weight, manufacturer);
this.energy = 30.0;
}
#Override
public void start() {
System.out.println("This is a Human Study Robot");
System.out.println("The robot has started studying.");
}
#Override
public void stop() {
System.out.println("The robot has finished studying.");
}
#Override
public void doTask() {
study();
walk();
}
#Override
public void doTask(Scanner input) {
// TODO Auto-generated method stub
}
public void study() {
if (energy >= energyRequired()) {
energyConsumption();
}
else
if (energy < energyRequired()) {
System.out.println("The robot does not have sufficient energy.");
regenerate();
System.out.println("................");
System.out.println("The robot has finished regenerating");
}
}
public String toString() {
return "I AM A HUMAN STUDY ROBOT : \nThe details of the human study robot are below:\n"
+ "Name : " + getName() + "\nWeight: " + getWeight() + "\nHeight: "
+ getHeight() + "\nManufacturer : " + getManufacturer() + "\nPurpose : "
+ getPurpose();
}
public void walk() {
int steps;
boolean valid = false;
Scanner input = new Scanner(System.in);
System.out.println("Would you like me to walk for you?");
if (input.nextLine().equalsIgnoreCase("Y")){
do {
System.out.println("I can only walk 10 paces at a time");
System.out.println("For how many paces? ( Enter a no. between 1 and 10 )");
while (!input.hasNextInt()) {
System.out.println("That is not a number");
input.nextLine();
}
steps = input.nextInt();
valid = true;
} while(steps < 0 || steps > 10);
System.out.println("Which direction do you want me to walk? ( Enter a number between 1 and 4, the options are below.");
System.out.println("1 - " + Directions.FORWARD);
System.out.println("2 - " + Directions.BACKWARD);
System.out.println("3 - " + Directions.LEFT);
System.out.println("4 - " + Directions.RIGHT);
int selection = input.nextInt();
if (selection == 1 ) {
setDirection(Directions.FORWARD);
} else if (selection == 2 ) {
setDirection(Directions.BACKWARD);
} else if (selection == 3 ) {
setDirection(Directions.LEFT);
} else if (selection == 4 ) {
setDirection(Directions.RIGHT);
}
else System.out.println("That is not a valid selection.");
System.out.println("I have walked " + getDirection() + " " + steps + " steps");
}
}
}

You did'nt write the foreach loop in a right way ...
for (Robot eachRobot : Robots) { //for loop to go through the array list
System.out.println(Robots.toString());
System.out.println("\n");
}
And this will print the whole list elements as :
ArrayList<Integer>lists=new ArrayList<Integer>();
lists.add(new Integer(50));
lists.add(new Integer(70));
for (Integer integer : lists) {
System.out.println(lists.toString());
}
will print :
[50, 70]
[50, 70]
So change the loop to print each element toString function It should written like :
for (Robot eachRobot : Robots) { //for loop to go through the array list
System.out.println(eachRobot .toString()+"\n");
// println is already print new line for you if you want to print two lines you can use that instead.
}
Rewrite the loop and test ..

Need guidance on a simple pig game that terminates and ends

I am trying to create a simple Pig game.. The problem that i have is that the program terminates.
For example, when i run it, entering two players and two names works perfectly, and so does the first round.. as soon as i enter n, and the turn goes to player 2, the program just stops.. I would like it to continue until the score is reached..
Below is my code.. I would appreciate ANY help.. I am totally lost on this one..
And yes... I am a beginner..
Thank you!!
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Scanner;
public class PigGame {
public static void main(String[] args) {
ArrayList<Player> users = initialize();
for (Player p : users) {
System.out.println(p.getNick() + "'s turn!");
System.out.println("Your score is: " + p.getScoreTotal() + "!");
takeTurn(p);
if (p.getScoreTotal() >= 100) {
System.out.println(p.getNick() + "wins! Congratulations");
return;
}
}
}
private static ArrayList<Player> initialize() {
Scanner sc = new Scanner(System.in);
System.out.println("Welcome to Pig!");
System.out.println("How many will play the game?");
int qusers = sc.nextInt();
sc.nextLine();
ArrayList<Player> users = new ArrayList();
for (int i = 1; i <= qusers; i++)
{
System.out.println("Enter the name of player " + i + ":");
users.add(new Player(sc.nextLine(), 1, 6));
}
return users;
}
private static void takeTurn(Player p) {
String input = "";
int currentScore = 0;
Scanner sc = new Scanner(System.in);
do {
p.rollDice();
currentScore += p.getDieWorth();
System.out.println(p.getNick() + "'s dice rolled " + p.getDieWorth());
if (p.getDieWorth() != 1) {
System.out.println("Your score is: " + currentScore + " for this round.");
System.out.println("Do you want to roll again? (j/n)");
input = sc.nextLine();
} else {
System.out.println("Sorry");
currentScore = 0;
}
}
while ((input.equals("j")) && (p.getDieWorth() != 1));
p.increaseScore(currentScore);
}
}

Here's your code.
for (Player p : users) {
System.out.println(p.getNick() + "'s turn!");
System.out.println("Your score is: " + p.getScoreTotal() + "!");
takeTurn(p);
if (p.getScoreTotal() >= 100) {
System.out.println(p.getNick() + "wins! Congratulations");
return;
}
}
This only goes through the users once. for goes through each user and then it's done. You need a while loop.
//this is somewhat messy, but it gets the point across
Player p = users.get(0);
int playerIndex = users.size();
while(p.getScoreTotal() < 100) {
if(playerIndex == users.size()) {
playerIndex = 0;
}
p = users.get(playerIndex);
playerIndex++;
System.out.println(p.getNick() + "'s turn!");
System.out.println("Your score is: " + p.getScoreTotal() + "!");
takeTurn(p);
}
System.out.println(p.getNick() + "wins! Congratulations");
return;

Very simple game about Guessing The Number

/hello, I am trying to learn how to use "break" commend in java as well as continuing loop with "y or n" choice. I am writing this game Guessing Number and I have some trouble with "y" choice. I will try to explain, to write a game of guessing number was easy so I started to add some conditions like the possibility on the and to play again or not, later I was thinking that would be more interesting if I add possibility to quit any time player wish, but that does not working correctly. Please help, thats my code
package guessinggame;
import java.util.Random;
import java.util.Scanner;
/**
*
public class Main {
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
System.out.println(" Welcome ");
Random rand = new Random();
Scanner input = new Scanner(System.in);
boolean play_again = true;
while (play_again)
{
int number_guess = rand.nextInt(100)+1;
int number_of_tries = 0;
int guess;
String another = "y";
boolean win = false;
while (win == false)
{
System.out.println(" Try too guess a number between 1 and 100 ");
guess = input.nextInt();
number_of_tries++;
if (guess == number_guess)
{
win = true;
}
else if (guess < number_guess)
{
System.out.println(" Guess is too low " + "\n Guess another number to continue or n to quit ");
if (input.hasNext("n"))
{
play_again = false;
break;
}
}
else if (guess > number_guess)
{
System.out.println(" Guess is too high " + "\n Guess another number to continue or n to quit ");
if (input.hasNext("n"))
{
play_again = false;
break;
}
}
}
System.out.println(" You Win!!! ");
System.out.println(" The number was " + number_guess);
System.out.println(" It took you " + number_of_tries + " tries " +
"\nWould you like to play again? (y/n): ");
if (another.equalsIgnoreCase("y") == true)
play_again = true;
else
{
play_again = false;
}
}
}
}

Here is an alternative that achieves that same outcome
public class Main {
/**
* #param args the command line arguments
*/
public static void main(String[] args)
{
System.out.println(" Welcome ");
Random rand = new Random();
Scanner input = new Scanner(System.in);
int guess = 0;
int number_of_tries = 0;
System.out.println(" Try too guess a number between 1 and 100 -1 to close");
guess = input.nextInt(); //get first input
while (guess != -1)
{
int number_guess = rand.nextInt(5) + 1;
++number_of_tries;
//check if user wins and exits loop
if (isWin (number_guess,guess))
{
System.out.println(" You Win!!! ");
System.out.println(" The number was " + number_guess);
System.out.println(" It took you " + number_of_tries + " tries " +
"\nWould you like to play again? [1 yes/ -1 no]: ");
guess = input.nextInt();
if (guess == -1)
break;
else
System.out.println(" Try too guess a number between 1 and 100 -1 to close");
}
else if (number_guess < guess )
{
System.out.println(" Guess is too High " + "\n Guess another number to continue or -1 to quit ");
guess = input.nextInt();
continue;
}
else if (number_guess > guess)
{
System.out.println(" Guess is too low " + "\n Guess another number to continue or -1 to quit ");
guess = input.nextInt();
continue;
}
}
System.out.println ("bye bye");
}
public static boolean isWin (int number,int guess)
{
return (number == guess) ? true :false;
}
}

You forgot to wait for user input after this statement:
System.out.println(" It took you " + number_of_tries + " tries " +
"\nWould you like to play again? (y/n): ");
E.g. you could try next approach:
System.out.println(" It took you " + number_of_tries + " tries " +
"\nWould you like to play again? (y/n): ");
if (input.hasNext()) {
if (another.equalsIgnoreCase("y")) {
play_again = true;
input.next();
} else {
play_again = false;
}
}

It looks like your braces are messed up for your play again if statement

This will work.
package aa;
import java.util.Random;
import java.util.Scanner;
public class abc {
public static void main(String[] args) {
System.out.println(" Welcome ");
Random rand = new Random();
Scanner input = new Scanner(System.in);
boolean play_again = true;
while (play_again)
{
int number_guess = rand.nextInt(100)+1;
int number_of_tries = 0;
int guess;
String another = "y";
boolean win = false;
while (win == false)
{
System.out.println(" Try too guess a number between 1 and 100 ");
guess = input.nextInt();
number_of_tries++;
if (guess == number_guess)
{
win = true;
break;
}
else if (guess < number_guess)
{
System.out.println(" Guess is too low " + "\n Guess another number to continue or n to quit ");
if (input.hasNext("n"))
{
play_again = false;
break;
}
}
else if (guess > number_guess)
{
System.out.println(" Guess is too high " + "\n Guess another number to continue or n to quit ");
if (input.hasNext("n"))
{
play_again = false;
break;
}
}
}
input.next();
if (win == true){
System.out.println(" You Win!!! ");
}
else{
System.out.println(" Good Luck Next Time!!! ");
System.out.println(" The number was " + number_guess);
}
System.out.println(" It took you " + number_of_tries + " tries " +
"\nWould you like to play again? (y/n): ");
another = input.next();
if (another.equalsIgnoreCase("y") == true)
play_again = true;
else
{
play_again = false;
}
}
System.out.println("Thank you!!!");
}
}