all!
I'm a university freshman computer science major taking a programming course. While doing a homework question, I got stuck on a certain part of my code. Please be kind, as this is my first semester and we've only been doing Java for 3 weeks.
For context, my assignment is:
"Create a program that will ask the user to enter their name and to enter the number of steps they walked in a day. Then ask them if they want to continue. If the answer is "yes" ask them to enter another number of steps walked. Ask them again if they want to continue. If they type anything besides "yes" you should end the program by telling them "goodbye, [NAME]" and the sum of the number of steps that they have entered."
For the life of me, I can not get the while loop to end. It's ignoring the condition that I (probably in an incorrect way) set.
Can you please help me and tell me what I'm doing wrong?
import java.util.Scanner;
public class StepCounter
{
/**
* #param args the command line arguments
*/
public static void main(String[] args)
{
final String SENTINEL = "No";
String userName = "";
String moreNum = "";
int numStep = 0;
int totalStep = 0;
boolean done = false;
Scanner in = new Scanner(System.in);
Scanner in2 = new Scanner(System.in);
// Prompt for the user's name
System.out.print("Please enter your name: ");
userName = in.nextLine();
while(!done)
{
// Prompt for the number of steps taken
System.out.print("Please enter the number of steps you have taken: ");
// Read the value for the number of steps
numStep = in.nextInt();
// Prompt the user if they want to continue
System.out.print("Would you like to continue? Type Yes/No: ");
// Read if they want to continue
moreNum = in2.nextLine();
// Check for the Sentinel
if(moreNum != SENTINEL)
{
// add the running total of steps to the new value of steps
totalStep += numStep;
}
else
{
done = true;
// display results
System.out.println("Goodbye, " + userName + ". The total number of steps you entered is + " + totalStep + ".");
}
}
}
}
To compare the contents of String objects you should use compareTo function.
moreNum.compareTo(SENTINEL) return 0 if they are equal.
== operator is used to check whether they are referring to same object or not.
one more issue with addition of steps, addition should be done in case of "No" entered also
Use
if(!moreNum.equals(SENTINEL))
Instead of
if(moreNum != SENTINEL)
Also, make sure to add: totalStep += numStep; into your else statement so your program will actually add the steps together.
Related
I am incredibly new to java and have been given the following task:
Write a Java Program to prompt a user for a 3 letter body part name which has to be in the 'official' list of 3 letter body parts. (Arm, Ear, Eye, Gum, Hip, Jaw, Leg, Lip, Rib, Toe)
If a user makes a guess correctly then display the correct guess as part of a list.
Allow the user to keep guessing until they have all 10.
If a body part is incorrect then display an appropriate message.
Display the number of guesses they have made including
the correct ones.
The advice given was to use Arrays and Collections as well as Exception Handling where appropriate but I don't know where to go from what I've coded so far. Any help would be appreciated so much, thank you.
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
String[] bodyparts = new String [10];
bodyparts[0] = "Arm";
bodyparts[1] = "Ear";
bodyparts[2] = "Eye";
bodyparts[3] = "Gum";
bodyparts[4] = "Hip";
bodyparts[5] = "Jaw";
bodyparts[6] = "Leg";
bodyparts[7] = "Lip";
bodyparts[8] = "Rib";
bodyparts[9] = "Toe";
Set<String> bodypartSet = new TreeSet<>();
Collections.addAll(bodypartSet, bodyparts);
System.out.println("Please enter a 3 letter body part: ");
String bodypart = input.nextLine();
if (bodypartSet.contains(bodypart)) {
System.out.println("Correct, " + bodypart + " is on the list!");
} else {
System.out.println("Nope, try again!");
}
}
There are a lot of way to do this. The following, isn't the best or the most efficient, but it should work...
First of all, you have to put your "official" list in a structure, like an array:
private static String[] offList={Arm, Ear, Eye, Gum, Hip, Jaw, Leg, Lip, Rib, Toe};
Now you have to write a method that can find a world in that "offList", like that:
private static boolean find(String word){
for( int i=0; i<offList.length; i++){
if(word.equals(offList[i])) //if "word" is in offList
return true;
}
return false;
}
Now, let's create this guessing game GUI:
public static void main(String[] args){
LinkedList<String> guessed=new LinkedList<>();
String s;
Scanner input = new Scanner(System.in);
while(guessed.size()<offList.length){
System.out.println("Guessed= "+guessed.toString()); //you have to change it, if you want a better look
System.out.print("Try:");
s=input.nextLine();
/*Here we ask to the user the same thing, unless the guessed list
contains all the words of offList.
Every time we print the guessed worlds list*/
if(find(s)){
System.out.println("This world is in offList!");
if(!guessed.contains(s)) //the world is counted only one time!
guessed.add(s);
}else
System.out.println("Sorry...");
}
System.out.println("The complete list is "+guessed.toString());
}
If you want to show this game in a window, you should have to study some Java Swing classes.
EDIT: I post my answer before the main post editing. First of all you have to understand the Collections advantages and usage... When you know all the LinkedList methods, for example, this assignment looks like a joke! ;)
You need a loop for that, otherwise it will only ask for input once.
Something like this should do:
ArrayList<String> bodyParts = new ArrayList<String>();
bodyParts.add("Arm");
bodyParts.add("Ear");
bodyParts.add("Eye");
bodyParts.add("Gum");
bodyParts.add("Hip");
bodyParts.add("Jaw");
bodyParts.add("Leg");
bodyParts.add("Lip");
bodyParts.add("Rib");
bodyParts.add("Toe");
String input = "";
int totalGuesses = 0;
Scanner sc = new Scanner(System.in);
System.out.println("Start guessing...");
while (!bodyParts.isEmpty()) {
totalGuesses++;
input = sc.nextLine();
if (input.length() != 3 || !bodyParts.contains(input)) {
// incorrect, do nothing
System.out.println("Nope.");
} else {
// correct, remove entry
bodyParts.remove(input);
System.out.println("Correct! " + (10 - bodyParts.size()) + " correct guess" + ((10 - bodyParts.size()) != 1 ? "es" : ""));
}
}
System.out.println("Done. You have found them all after " + totalGuesses + " guesses.");
sc.close();
Also, this is case sensitive. It will not find Arm when typing arm. And if you need the number of all guesses you can simply add an int before the loop and increase it inside.
The result of my example:
Start guessing...
arm
Nope.
Arm
Correct! 1 correct guess
Arm
Nope.
Ear
Correct! 2 correct guesses
Eye
Correct! 3 correct guesses
(...)
Rib
Correct! 9 correct guesses
Toe
Correct! 10 correct guesses
Done. You have found them all after 12 guesses.
I am taking the first Java class and working on my second project. The project is about creating an program as a network of rooms on a virtual three-dimensional work area. Each room provides a virtual environment that together can be assemble into a simulated or virtual world.
Basically, the beginning of the program, I used while loop, and at the end I want to ask user if he/she wants to quit the program, and print a thank you message. However, the while loop does not work. My program quit no matter I entered y or n. Below is my codes.
import java.util.Scanner;
public class Project
{
public static void main(String[] args)
{
Map map = new Map();
int floor = 0;
int row = 0;
int col = 0;
String input = " ";
Scanner scan = new Scanner(System.in);
// Begin user dialog. Welcome message
System.out.println("Welcome to the L.A Underground! (Verson 1.1)");
System.out.println();
String choice = "y";
while(!input.equalsIgnoreCase("quit"))
{
input = scan.nextLine().toLowerCase();
// My codes are here
if (input.equals("south")
{statement}
else
System.out.println("You can't go that way.");
else if (input.equals("quit"))
{ // See if user wants to continue
System.out.println("Do you wish to leave the Underground (Y/N)? >");
choice = scan.nextLine();
System.out.println();
}
// if user enters other words than quit
else
System.out.println("I don't recognize the word '" + input +"'");
}
System.out.println("Thank you for visiting L.A Underground.");
}
}
When I typed "quit" the console printed the message: "Do you wish to leave the Underground? (Y/N)? >". I tried Y/N (y/n) the program terminated. Any help is appreciated. Thank you.
Updated: Sorry for the confusion. What I wanted the program to run is when the user types "quit", the message will print out "Do you wish to leave the Underground (Y/N)?>?" , and if the user types "hello", the message will be "I don't understand the word 'hello'". And when the user type y, the program will quit, otherwise (type n), the program will start over again.
Ask for user input inside of your loop. If input.equalsIgnoreCase("quit"), then prompt the user an "are you sure" message. If the input.equalsIgnoreCase("y"), then break the loop, otherwise, keep going.
Scanner scan = new Scanner(System.in);
String input;
// Begin user dialog. Welcome message
System.out.println("Welcome to the L.A Underground! (Verson 1.1)");
System.out.println();
while (true) {
input = scan.nextLine();
if (input.equalsIgnoreCase("quit")) {
System.out.print("Do you wish to leave the Underground (Y/N)? >");
if (scan.nextLine().equals("y")) {
break;
}
}
// input wasn't "quit", so do other stuff here
}
System.out.println("Thank you for visiting L.A Underground.");
Your code loops until it gets "quit" ... then asks for "yes/no" ... then simply exits, regardless.
You need to change your loop, so that it includes BOTH "MY CODES HERE" AND the "quit y/n" check.
EXAMPLE:
...
boolean done = false;
while(!done) {
//MY CODES ARE HERE
if (input.equalsIgnoreCase("quit") && getYesNo ()) == 'y') {
done = true;
}
}
"getYesNo()" is a method you write. For example:
char getYesNo () {
System.out.print("Do you wish to leave the Underground (Y/N)? >");
String line = scan.nextLine();
return line.charAt(0);
}
In the code you've posted, your loop is being controlled by the condition !input.equalsIgnoreCase("quit"). That is, if input is "quit", the loop is terminated.
But the following block is executed only if input is "quit":
if (input.equals("quit"))
{
// See if user wants to continue
System.out.println("Do you wish to leave the Underground (Y/N)? >");
choice = scan.nextLine();
System.out.println();
}
So if this block is executed, !input.equalsIgnoreCase("quit") evaluates to false and the loop is terminated. And that's not what you want.
Now that you know what's wrong, fixing it is easy. Check the value of choice in the above if block: if choice is not yes, don't quit i.e. reset input to a default value.
I've pasted the working code here on pastebin.
I'm very new to programming, especially Java. I need to create a program that counts how many orders each entry at a restaurant gets ordered. The restaurant carries 3 entries, hamburgers, salad, and special.
I need to set up my program so that the user inputs, say, "hamburger 3", it would keep track of the number and add it up at the end. If the user inputs "quit", the program would quit.
System.out.println("Enter the type (special, salad, or hamburger) of entrée followed by the number, or quit to exit the program.");
I'm thinking about using a while loop, setting it so if the user input != to "quit", then it would run.
What's difficult for me is I don't know how to make my program take into account the two different parts of the user input, "hamburger 3" and sum up the number part at the end.
At the end, I want it to say something like "You sold X hamburgers, Y salads, and Z specials today."
Help would be appreciated.
You'll probably want three int variables to use as a running tally of the number of orders been made:
public class Restaurant {
private int specials = 0;
private int salads = 0;
private int hamburger = 0;
You could then use a do-while loop to request information from the user...
String input = null;
do {
//...
} while ("quite".equalsIgnoreCase(input));
Now, you need some way to ask the user for input. You can use a java.util.Scanner easily enough for this. See the Scanning tutorial
Scanner scanner = new Scanner(System.in);
//...
do {
System.out.println("Enter the type (special, salad, or hamburger) of entrée followed by the number, or quit to exit the program.");
input = scanner.nextLine();
Now you have the input from the user, you need to make some decisions. You need to know if they entered valid input (an entree and an amount) as well as if they entered an available option...
// Break the input apart at the spaces...
String[] parts = input.split(" ");
// We only care if there are two parts...
if (parts.length == 2) {
// Process the parts...
} else if (parts.length == 0 || !"quite".equalsIgnoreCase(parts[0])) {
System.out.println("Your selection is invalid");
}
Okay, so we can now determine if the user input meets or first requirement or not ([text][space][text]), now we need to determine if the values are actually valid...
First, lets check the quantity...
if (parts.length == 2) {
// We user another Scanner, as this can determine if the String
// is an `int` value (or at least starts with one)
Scanner test = new Scanner(parts[1]);
if (test.hasInt()) {
int quantity = test.nextInt();
// continue processing...
} else {
System.out.println(parts[1] + " is not a valid quantity");
}
Now we want to check if the actually entered a valid entree...
if (test.hasInt()) {
int quantity = test.nextInt();
// We could use a case statement here, but for simplicity...
if ("special".equalsIgnoreCase(parts[0])) {
specials += quantity;
} else if ("salad".equalsIgnoreCase(parts[0])) {
salads += quantity;
} else if ("hamburger".equalsIgnoreCase(parts[0])) {
hamburger += quantity;
} else {
System.out.println(parts[0] + " is not a valid entree");
}
Take a look at The if-then and if-then-else Statements and The while and do-while Statements for more details.
You may also find Learning the Java Language of some help. Also, keep a copy of the JavaDocs at hand, it will make it eaiser to find references to the classes within the API
These two methods should be what you're looking for.
For splitting: String.split(String regex)
http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#split(java.lang.String)
For parsing String into an Interger: Integer.parseInt(String s)
http://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html#parseInt(java.lang.String)
You can split your strings using input.split(" "). This method gives you two strings - two parts of the main string. The character you splitted with (" ") won't be found in the string anymore.
To then get an integer out of your string, you can use the static method Integer.parseInt(inputPartWithCount).
I hope this helps!
So everything is working fine for this calculator besides for the askCalcChoice1. Since askCalcChoice1 is a string, I am calling it wrong (obviously). The error says it cannot convert string to int, as well as convert int to boolean. However, when i make the inputOperation as a string, it breaks the other 2 calls below askCalcChoice1. (it breaks displayRedults and askTwoValues because those are not strings). I do not know how to format askCalcChoice in order to call for this method that is written in another class wihtout breaking anything. askCalcChoice is written as a string which i pasted below the oopCalculator code. Is there any way and can someone please show me how to write that portion of that code in oopCalculator?
int inputOperation; // user to choose the function
askCalcChoice1 myAskCalcChoice1 = new askCalcChoice1();
//menu becomes a complete string below
String menu = "Welcome to Hilda Wu's Calculator\t\t"
+ "\n1. Addition\n"
+ "2. Subtraction\n"
+ "3. Multiplication\n"
+ "4. Division\n"
+ "5. Exit\n\n";
calculatorCommands.pickNewSymbol(menu); //complete menu will be picked up as a string and display
calculatorCommands.putDownSymbol();
while (inputOperation = myAskCalcChoice1.calcChoice()) { //this will call for myAskCalcChoice1 class
calculatorCommands.pickNewSymbol("\n"); //pick up the class
calculatorCommands.putDownSymbol(); //display the class
askTwoValues myAskTwoValues = new askTwoValues();
float[] myFloats = myAskTwoValues.inputFloats(inputOperation);
displayResults myDisplayResults = new displayResults();
float result = myDisplayResults.showResults(inputOperation, myFloats);
String strFormat = "The answer is: " + result + "\n\n"; //print out The answer is as a string
calculatorCommands.pickNewSymbol(strFormat); //pick up string from above
calculatorCommands.putDownSymbol(); //display string
calculatorCommands.pickNewSymbol(menu); // pick up menu from the beginning of code, loop to calculator menu
calculatorCommands.putDownSymbol(); //display menu as loop
}
calculatorCommands.pickNewSymbol("\nThank you for using Hilda Wu's Calculator\n"); //when user choose to exit calculator
calculatorCommands.putDownSymbol();
}
String calcChoice() {
String input;
do { //do loop will continue to run until user enters correct response
System.out.print("Please enter a number between 1 and 5, A for Addition, S for Subtraction, M for Multiplication, or D for Division, or X for Exit: ");
try {
input = readInput.nextLine(); //user will enter a response
if (input.equals("A") || input.equals("S") || input.equals("M") || input.equals("D") || input.equals("X")) {
System.out.println("Thank you");
break; //user entered a character of A, S, M, or D
} else if (Integer.parseInt(input) >= 1 && Integer.parseInt(input) <= 5) {
System.out.println("Thank you");
break; //user entered a number between 1 and 5
} else {
System.out.println("Sorry, you have entered an invalid choice, please try again.");
}
continue;
}
catch (final NumberFormatException e) {
System.out.println("You have entered an invalid choice. Try again.");
continue; // loop will continue until correct answer is found
}
} while (true);
return input;
}
}
To start with, you are calling showResults with two arguments:
int choice
and
float [] f
Choice is never used.
You use input variable instead in your switch but on default you return the error showing choice.
Better pass choice as an argument in the function and be sure it is char and not other type.
Also this is not the form of a good stated question. I will not rate it down but please remake it so the whole code is correctly shown. I can not make sense of it easily. I might misunderstood it already. Please do not add comments between, be sure you have correct indentation and you got all the code in.
If you need to comment do it afterwards. It's not very complicated, just show us the code and ask what is wrong later ;)
If choice was meant to pass in the switch... then do it, but not as int but as char.
I have a college assignment where I need to print out items sold by a hardware store, take input from a user, perform some calculations on that input, and then print out an invoice.
I have been able to successfully print out the items sold by the hardware store, but am encountering problems with the while loop that takes the input.
The program asks the user to enter a CODE and then asks for the corresponding QUANTITY. This works fine on the first iteration of the loop, but on the second iteration the user prompts for "CODE:" and "QUANTITY:" appear on the same line, despite my use of println when prompting the user.
I would greatly appreciate a detailed response appropriate for someone new in programming.
Here's the code:
import java.util.Scanner;
class HardwareStore {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.println("WELCOME TO THE HARDWARE STORE!");
System.out.println("----------------------------------------------------------------------");
String sticky = "G22";
String keyring = "K13";
String screwy = "S21";
String padlock = "I30";
int stickyprice = 10989;
int keyringprice = 5655;
int screwyprice = 1099;
int padlockprice = 4005;
System.out.println("CODE\t\tDESCRIPTION\t\t\t\t\tPRICE");
System.out.println("----\t\t-----------\t\t\t\t\t-----");
System.out.println(sticky + "\t\tSTICKY Construction Glue, Heavy Duty, \n\t\t7oz, 12 Pack \t\t\t\t\t$" + stickyprice);
System.out.println(keyring + "\t\tCAR-LO Key Ring, Quick Release, \n\t\t1 Pack\t\t\t\t\t\t$ " + keyringprice);
System.out.println(screwy + "\t\t!GREAT DEAL! SCREW-DUP Screwy Screws, \n\t\tDry Wall Screws, 3 in. Long, 50 Pack\t\t$ " + screwyprice);
System.out.println(padlock + "\t\tLET-IT-RAIN, Weather Proof Padlock, \n\t\tPortable, One Push Functionality\t\t$ " + padlockprice);
System.out.println("----------------------------------------------------------------------");
int i = 10000;
String [] usercode = new String[i];
int [] userquantity = new int[i];
System.out.println("PLEASE ENTER YOUR ORDER:");
while (true) {
System.out.println("CODE: (X to terminate)");
usercode[i] = in.nextLine();
if (usercode[i].equalsIgnoreCase("x")) {
break;
}
System.out.println("QUANTITY: ");
userquantity[i] = in.nextInt();
}
}
}
when you enter the QUANTITY you're pressing enter. That newline character isn't used by in.nextInt();, it remains in the scanner buffer, until you roll around to in.nextLine() again.
At that point in.nextLine() reads until it finds a newline character, which just happens to be the next one in the buffer. So it skips straight to QUANTITY again.