I'm just starting Java and this is a coin flip program that I've written recently. So it's supposed to produce sequences of coin flips that meet the requirements that the user sets, however when it gets to the end it should ask if the user wants to go again. I'm having an issue where it will print the question twice when it gets down to end. I really need to figuer this out so any suggestions/clarifications for my code would be greatly appreciated.
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
outer: while (true) {
System.out.print("Ready to run a coin flip simulation. Enter the number of sequences: ");
int sequences = scan.nextInt();
System.out.print("How many heads should each sequence have? ");
int heads = scan.nextInt();
System.out.print("How many tails should each sequence have? ");
int tails = scan.nextInt();
System.out.println("Simulating Sequences");
int tFlips = 0;
int mFlips = 0;
for (int i = 1; i <= sequences; i++) {
int h = 0;
int t = 0;
String s = "";
while (t < tails || h < heads) {
if (Math.random() < 0.5) {
h++;
s += "H";
} else {
t++;
s += "T";
}
tFlips++;
}
if (t + h > mFlips) {
mFlips = t + h;
}
System.out.println(i + " - " + s);
h = 0;
t = 0;
s = "";
}
System.out.printf("The average number of flips was " + ((float) tFlips / sequences) + " and maximum was %d", mFlips);
System.out.println("\r\n");
boolean go = true;
while (go) {
System.out.print("Would you like to run another simulation? (y/n): ");
String c = scan.nextLine();
if (c.equalsIgnoreCase("y")) {
break;
} else if (c.equalsIgnoreCase("n")) {
break outer;
} else {
continue;
}
}
System.out.print("\r\n");
}
}
Your String c = scan.nextLine(); reads a new line from your scan.nextInt() calls. You can read more here Scanner is skipping nextLine() after using next() or nextFoo()?
It is good practice to call .nextLine() after every call to .nextInt() to always consume the newline character.
Change the String c = scan.nextLine(); to String c = scan.next();. And you don't really need the while(go) loop, it's more simple if you're doing this:
System.out.print("Would you like to run another simulation? (y/n): ");
String c = scan.next();
if (!c.equalsIgnoreCase("y"))
break;
P.S.: here is a good answer why the nextLine() isn't working correctly. (by #Rohit Jain)
Related
must create a java application that will determine and display sum of numbers as entered by the user.The summation must take place so long the user wants to.when program ends the summation must be displayed as follows
e.g say the user enters 3 numbers
10 + 12+ 3=25
and you must use a while loop
Here's a function to do just that. Just call the function whenever you need.
Ex: System.out.println(parseSum("10 + 12+ 3")) → 25
public static int parseSum(String input) {
// Removes spaces
input = input.replace(" ", "");
int total = 0;
String num = "";
int letter = 0;
// Loop through each letter of input
while (letter < input.length()) {
// Checks if letter is a number
if (input.substring(letter, letter+1).matches(".*[0-9].*")) {
// Adds that character to String
num += input.charAt(letter);
} else {
// If the character is not a number, it turns the String to an integer and adds it to the total
total += Integer.valueOf(num);
num = "";
}
letter++;
}
total += Integer.valueOf(num);
return total;
}
The while loop is essentially a for loop though. Is there a specific reason why you needed it to be a while loop?
There is a lot of ways to achieve this. Here an example of code that could be improve (for example by catching an InputMismatchException if the user doesn't enter a number).
Please for the next time, post what you have tried and where you stuck on.
public static void main (String[] args) {
boolean playAgain = true;
while(playAgain) {
Scanner sc = new Scanner(System.in);
System.out.println("Please enter the first number : ");
int nb1 = sc.nextInt();
System.out.println("Ok! I got it! Please enter the second number : ");
int nb2 = sc.nextInt();
System.out.println("Great! Please enter the third and last number : ");
int nb3 = sc.nextInt();
int sum = nb1+nb2+nb3;
System.out.println("result==>"+nb1+"+"+nb2+"+"+nb3+"="+sum);
boolean validResponse = false;
while(!validResponse) {
System.out.println("Do you want to continue ? y/n");
String response = sc.next();
if(response.equals("n")) {
System.out.println("Thank you! see you next time :)");
playAgain = false;
validResponse = true;
} else if(response.equals("y")) {
playAgain = true;
validResponse = true;
} else {
System.out.println("Sorry, I didn't get it!");
}
}
}
}
I'm still learning Java and me and my classmate are working on this assignment code game hangman. We have a problem in the part printing the original word, because we want the word to be hidden, but we need the word to be printed, not hidden on the final output. What can we revise in our code to make it print properly??
import java.util.Scanner;
public class GameHangman {
public static void main(String[] args) {
System.out.println("Welcome! To the HANGMAN game.");
System.out.println("Guess the word by guessing each letter.");
System.out.println("LET'S START!");
String[] words = {"superman","batman","spiderman"};
int t = words.length;
int x, y, miss;
String w;
char l, c='y';
Scanner input = new Scanner(System.in);
while (c=='y')
{
x = (int)(Math.random()*(t));
w = words[x];
char[]chars = w.toCharArray();
var hidden = new char[w.length()];
for(int i = 0; i < hidden.length; i++)
{
hidden[i] = '*';
}
boolean z = false;
int count = 0;
miss = 0;
while(!z)
{
System.out.print("\n(guess) Enter a letter ("+new String(hidden)+"): ");
l = input.next().charAt(0);
y = 0;
for(int i = 0; i < hidden.length; i++)
{
if(chars[i]==l)
{
y++;
if(hidden[i]=='*')
{
hidden[i]=l;
count++;
y++;
}
}
}
if(y==1)System.out.println("\nOOPS!("+l+") already present, try other letters.");
else if (y==0)
{
miss++;
System.out.println("\nYIKES!("+l+") is not in the word, guess again.");
}
if(count==hidden.length) z = true;
}
System.out.println("\nGreat!! You guessed the word("+hidden+")!!!");
System.out.println("You were wrong "+miss+" tries.");
System.out.print("\nDo you want to continue with another game word? "
+ "\nEnter yes or no: ");
c = input.next().charAt(0);
}
}
}
in this part, we print our final word
System.out.println("\nGreat!! You guessed the word("+hidden+")!!!");
and this is what we are getting output. we need to print with not being hidden.
Here are two methods to convert your char array hidden into a String for printing out.
// First option: Create a String object
String str1 = new String(hidden);
System.out.println("\nGreat!! You guessed the word("+str1+")!!!");
// Second option: Using valueOf method
String str2 = String.valueOf(hidden);
System.out.println("\nGreat!! You guessed the word("+str2+")!!!");
Alternatively, you can also print your String variable w and avoid calling these methods.
I need to build a simple automaton for my Automata class. I am using Java and I cannot figure out for the life of me why my program keeps exiting prematurely. I've tried debugging it, having print statements everywhere to figure out where it's stopping, and although I know where it stops, I do not see anything that would make the program stop working. The stoppage happens on line 27 (Right where I SOP "Enter a string of digits...".
Knowing me it's probably something simple, but I cannot figure this one out.
import java.util.*;
public class hw1 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Please indicate the number of states");
int numState = input.nextInt();
int[] state = new int[numState];
boolean[] accept = new boolean[numState];
for (int i = 0; i < numState; i++) {
System.out.println("Is the state q" + (i + 1) + " a final state? (Answer 1 for yes; 0 for no)");
int finalState = input.nextInt();
if (finalState == 1)
accept[i] = true;
} // for
System.out.println("Enter the number of symbols s: ");
int numSym = input.nextInt();
int[][] next = new int[numState][numSym];
for (int i = 0; i < numState; i++) {
for (int j = 0; j < numSym; j++) {
System.out.println("What is the number for the next state for q" + i + " when it gets symbol " + j);
next[i][j] = input.nextInt();
}//nested for
}//for
String digits = input.nextLine();
System.out.print("Enter a string of digits (0-9) without spaces to test:");
int[] digitArray = new int[digits.length()];
for (int i = 0; i < digits.length(); i++) {
digitArray[i] = digits.charAt(i);
}
for (int i = 0; i < digits.length(); i++) {
System.out.print(digitArray[i] + " ,");
}
System.out.println("end of program");
}// main;
}// class
Change your code to :
input.nextLine();
System.out.print("Enter a string of digits (0-9) without spaces to test:");
String digits = input.nextLine();
This will get and ignore the newline character left in the stream after call to nextInt()
I have a little averaging program I have made and, I am trying to only allow it to take in numbers. Everything else works but, I can't seem to figure it out. I am still learning so, any advise or pointers would be awesome!
Here is my code.
import java.util.Scanner;
public class THISISATEST {
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
int sum = 0;
int count = 0;
int i = 1;
while (i <= 10) {
i++;
{
System.out.print("Enter the test score: ");
int tS = keyboard.nextInt();
count++;
sum = (sum + tS);
}
System.out.println(sum);
}
System.out.println("The Average is = " + sum / count);
}
}
Inside your while loop use the following code:
System.out.print("Enter the test score: ");
while (!keyboard.hasNextInt()) {//Will run till an integer input is found
System.out.println("Only number input is allowed!");
System.out.print("Enter the test score: ");
keyboard.next();
}
int tS = keyboard.nextInt();
//If input is a valid int value then the above while loop would not be executed
//but it will be assigned to your variable 'int ts'
count++;
sum = (sum + tS);
I'm trying to ask the user to enter any number of numbers up to 5, each number seperated by space.
for example
enter up to 5 numbers : 3 4 5
I'm going to add them in the integer sum and then later divide them by counter
to get the average of these numbers.
However, my loop does not seem to end. What's wrong with my code?
int counter = 0 , sum = 0;
Scanner scan = new Scanner(System.in);
System.out.println("enter up to 5 numbers");
while(scan.hasNextInt());{
counter++;
sum += scan.nextInt();
}
System.out.println(counter);
System.out.println(sum);
You put a ; between while and {, so it loops. Remove it.
Scanner.hasNextInt() does not do what you seem to think it does. It does not tell you whether there is an integer available in already typed input (it does not have any conception of what has "been typed"), but rather whether the input waiting can be read as an integer. If there is no input already waiting, it will block until there is, so your loop is simply sitting there forever, blocking for more input.
What you probably want to do instead is to read a whole line, and then split it explicitly into space-separated parts, and only then parse those as integers. For example, like this:
String input = scan.nextLine();
for(String part : input.split(" "))
sum += Integer.parseInt(part);
Serge Seredenko's answer is also correct, however, but that's another problem.
Everything in your code is fine except the semicolon(;) just after the while loop, of course it will lead to an infinite loop.
int counter = 0 , sum = 0;
Scanner scan = new Scanner(System.in);
System.out.println("enter up to 5 numbers");
while(scan.hasNextInt()){
counter++;
sum += scan.nextInt();
if(counter >=5)
break;
}
System.out.println(counter);
System.out.println(sum);
scan.close();
First, you need to remove ';' located after while(scan.hasNextInt()) and before {; For the ; means the while statement is complete.
Second, when you use your code, you need CTRL + Z to end up your input. By adding
if(counter >=5)
break;
your input will end up when you input 5 numbers.
If you want to read entire line and then do arithmetic operation later then you dont need to have while loop with hasNextInt() method.
I would suggest you to read line then split by space and iterate over string array. Check out code snippet.
package com.gaurangjadia.code.java;
import java.util.Scanner;
public class SO19204901 {
public static void main(String[] args) {
int counter = 0,
sum = 0;
System.out.println("enter up to 5 numbers");
Scanner scan = new Scanner(System.in);
String strInput = scan.nextLine();
String[] arrayNumbers = strInput.split(" ");
for (int i = 0; i < arrayNumbers.length; i++) {
int n;
try {
n = Integer.parseInt(arrayNumbers[i]);
}
catch (NumberFormatException e) {
n = 0;
}
sum = sum + n;
counter++;
}
System.out.println(sum);
}
}
DataInputStream in = new DataInputStream(System.in);
String[]label = {"quiz #","Total","Average"};
int counter = 0;
int theSum = 0;
System.out.print("Enter up to 5 number : ");
String[]tempNum = in.readLine().trim().split("\\s+");
System.out.println();
while (counter <= tempNum.length)
{
if ( counter == tempNum.length)
{
System.out.printf("%10s %12s\n",label[1],label[2]);
counter = 0;
break;
} else {
System.out.printf("%10s",label[0] + (counter+1) );
}
counter++;
}
while(counter <= tempNum.length)
{
if ( counter == tempNum.length)
{System.out.printf("%10d %10.2f\n",theSum,(double)(theSum/counter));
} else
{System.out.printf("%10d",Integer.valueOf(tempNum[counter]));
theSum += Integer.valueOf(tempNum[counter]);
}
counter++;
}