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How to make a method that loops back to the menu in java

I'm trying to get a code that gives several options to pick from and while I can get those to work it ends immediately after when I need it to go back to the options.
public static void main(String[] args) {
System.out.println("Hello, This is the math program");
System.out.println("Select an application from below: \n");
System.out.println("(1) pythagoraen");
System.out.println("(2) Subtraction");
System.out.println("(3) Multiplication");
System.out.println("(4) Division");
System.out.println("(5) Exit");
System.out.println("What is your Choice? ");
Scanner input = new Scanner(System.in);
int choice = input.nextInt();
if (choice == 1) {
pythagoraen();
System.out.println(pythagoraen());
} if (choice == 2) {
subtraction();
} if (choice == 3) {
multiplication();
} if (choice == 4) {
division();
} if (choice == 5){
exitprogam();
}
}
public static void subtraction(){
Scanner input = new Scanner( System.in );
int number1;
int number2;
int difference;
System.out.print( "Enter First integer: " );
number1 = input.nextInt();
System.out.print( "Enter Second integer: ");
number2 = input.nextInt();
difference = number1 - number2;
System.out.printf( "The difference is %d\n", difference);
}
I've tried several different while loops in an attempt to get it to return to the options but it either endlessly loops or doesn't work.
EDIT: I've added one of the methods to it as an example. the case suggestion doesn't work as I think the format it too different
public static void main(String[] args) {
System.out.println("Hello, This is the math program");
System.out.println("Select an application from below: \n");
System.out.println("(1) pythagoraen");
System.out.println("(2) Subtraction");
System.out.println("(3) Multiplication");
System.out.println("(4) Division");
System.out.println("(5) Exit");
System.out.println("What is your Choice? ");
Scanner input = new Scanner(System.in);
int choice = input.nextInt();
while(choice!=5){
if (choice == 1) {
pythagoraen();
System.out.println(pythagoraen());
} if (choice == 2) {
subtraction();
} if (choice == 3) {
multiplication();
} if (choice == 4) {
division();
} if (choice == 5){
exitprogam();
}
}}
Here's the only while code i can get to run. it infinitely loops itself.

Your best bet to achieve what you are looking to do is to use a Do-While loop. Pay attention to where you ask for the input and then should the choice be equal to your stopping condition, put that as the conditional in the while part of the loop.
While loops will run 0-N times, while Do-While loops always execute 1-N times. Use this to your advantage.
This is a good reference:
https://docs.oracle.com/javase/tutorial/java/nutsandbolts/while.html

You need to put the things you need to do over and over again, in a loop.
public static void main(String[] args) {
System.out.println("Hello, This is the math program");
System.out.println("Select an application from below: \n");
System.out.println("(1) pythagoraen");
System.out.println("(2) Subtraction");
System.out.println("(3) Multiplication");
System.out.println("(4) Division");
System.out.println("(5) Exit");
System.out.println("What is your Choice? ");
Scanner input = new Scanner(System.in);
int choice = input.nextInt();
while(choice!=5){
if (choice == 1) {
pythagoraen();
}
else if (choice == 2) {
subtraction();
}
else if (choice == 3) {
multiplication();
}
else if (choice == 4) {
division();
}
System.out.println("What is your next Choice? ");
choice = input.nextInt();
}
}
If you need the print the menu again, then you can put that also inside the loop. What you are doing here, is asking the user for input and then choosing the operation you want to do. Then at the end, you ask the user again about what to do next. If the user enters 5, the while condition becomes false and it exits the loop.
I also removed the if choice == 5 condition because the while loop will handle that scenario. Also added else before each if after the first one. That's for efficiency so that it doesn't check rest of the matches if it is matched with the first one.

There are many ways to achieve this but a better way to do it is with the use of a switch. With switch statements you can have a number of execution paths which seem to fit this situation better then the while loop being used. However, a while loop and a switch statement can not really be compared in terms of efficiency as they are fundamentally different, as can be seen in this article. here is how the implementation would look like with switches:
public static void main(String[] args) {
int exitFlag = 0;
int choice = showMenu();
do {
switch (choice) {
case 1:
System.out.println("pythagoraen()");
break;
case 2:
System.out.println("subtraction()");
break;
case 3:
System.out.println("multiplication()");
break;
case 4:
System.out.println("division()");
break;
case 5:
System.out.println("exitprogam()");
exitFlag = 1;
break;
default:
System.out.println("Invalid Option()");
break;
}
if (exitFlag != 1) {
choice = showMenu();
}
}while (choice != 5);
}
private static int showMenu() {
System.out.println("Hello, This is the math program");
System.out.println("Select an application from below: \n");
System.out.println("(1) pythagoraen");
System.out.println("(2) Subtraction");
System.out.println("(3) Multiplication");
System.out.println("(4) Division");
System.out.println("(5) Exit");
System.out.println("What is your Choice? ");
Scanner input = new Scanner(System.in);
int choice = input.nextInt();
return choice;
}
This is a lot cleaner and easier in the long run for refactoring. For more information on switches please refer to oracle docs.

Try this with the while loop
Scanner input = new Scanner(System.in);
int choice = input.nextInt();
while(choice != 5) {
Scanner input = new Scanner(System.in);
int choice = input.nextInt();
if (choice == 1) {
pythagoraen();
System.out.println(pythagoraen());
} if (choice == 2) {
subtraction();
} if (choice == 3) {
multiplication();
} if (choice == 4) {
division();
} if (choice == 5){
exitprogam();
}
}

Java Do While isn't working properly

Sorry I am new to this site so not sure how this will show up. I am trying to make a simple Rock, Paper, Scissors game. After the while statement, if R, P, S isn't entered, the program just does nothing. I want it to loop back to the question at the beginning so a right choice can be entered. Also, how would I enter a print statement like "Invalid Choice Please Retry"?
package rps.gameapp;
import java.util.Scanner;
public class RPSGameApp
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
String userChoice;
String playAgain;
int randNum = (int) (Math.random() * 3);
do
{
System.out.println("Welcome to Rock, Paper, Scissors Game.");
System.out.println("Pick R, P, or S.");
userChoice = sc.nextLine();
while (!userChoice.equalsIgnoreCase("P")
&& !userChoice.equalsIgnoreCase("R")
&& !userChoice.equalsIgnoreCase("S"));
String compChoice = "";
switch (randNum)
{
case 0:
compChoice = "R";
break;
case 1:
compChoice = "P";
break;
case 2:
compChoice = "S";
break;
}
System.out.println("The computer entered \"" + compChoice + "\".");
if (compChoice.equalsIgnoreCase(userChoice))
{
System.out.println("Draw");
} else if (userChoice.equalsIgnoreCase(userChoice)
&& compChoice.equalsIgnoreCase("S")
|| userChoice.equalsIgnoreCase("P")
&& compChoice.equalsIgnoreCase("R")
|| userChoice.equalsIgnoreCase("S")
&& compChoice.equalsIgnoreCase("P"))
{
System.out.println("User Wins");
} else
{
System.out.println("User Loses");
}
System.out.print(
"Do you want to play again? (Y/N)");
playAgain = sc.nextLine();
} while (playAgain.equalsIgnoreCase("Y"));
System.out.println("Thanks for Playing!");
}
}

It looks like you forgot one do for your inner do while loop.
It should be :
do {
do {
System.out.println("Welcome to Rock, Paper, Scissors Game.");
System.out.println("Pick R, P, or S.");
userChoice = sc.nextLine();
} while (!userChoice.equalsIgnoreCase("P") && !userChoice.equalsIgnoreCase("R") && !userChoice.equalsIgnoreCase("S"));
...
} while (playAgain.equalsIgnoreCase("Y"));
Without that inner do (and the curly braces surrounding that loop's body), the inner loop becomes a while loop with an empty body.

Like Eran said, you need to wrap your do-while loop in another loop, that will keep asking user for correct input. This is fully working code. One thing that could be better is the message after user inputs wrong letter.
Edit: also make sure you draw random number for every iteration.
Edit 2: to change the message depending on user input you can introduce a new variable that will keep the track of number of times you asked user for correct input. If it is 0- it means user is asked the first time and we should print "Welcome" message. It is anything other than 0- you need to ask the user for correct input. After every round we assign zero to the variable again and the cycle repeats. I have implemented this change in the code. Note that this variable can also be a boolean.
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String userChoice;
String playAgain;
int iterationNumber;
while (true) {
iterationNumber = 0;
do {
if (iterationNumber == 0) {
System.out.println("Welcome to Rock, Paper, Scissors Game.");
System.out.println("Pick R, P, or S.");
} else {
System.out.println("Please enter valid letter.");
System.out.println("Pick R, P, or S.");
}
iterationNumber++;
userChoice = sc.nextLine();
} while (!userChoice.equalsIgnoreCase("P")
&& !userChoice.equalsIgnoreCase("R")
&& !userChoice.equalsIgnoreCase("S"));
String compChoice = "";
int randNum = (int) (Math.random() * 3);
switch (randNum) {
case 0:
compChoice = "R";
break;
case 1:
compChoice = "P";
break;
case 2:
compChoice = "S";
break;
}
System.out.println("The computer entered \"" + compChoice + "\".");
if (compChoice.equalsIgnoreCase(userChoice)) {
System.out.println("Draw");
} else if (userChoice.equalsIgnoreCase("R")
&& compChoice.equalsIgnoreCase("S")
|| userChoice.equalsIgnoreCase("P")
&& compChoice.equalsIgnoreCase("R")
|| userChoice.equalsIgnoreCase("S")
&& compChoice.equalsIgnoreCase("P")) {
System.out.println("User Wins");
} else {
System.out.println("User Loses");
}
System.out.print(
"Do you want to play again? (Y/N)");
playAgain = sc.nextLine();
if (playAgain.equalsIgnoreCase("N")) {
break;
}
iterationNumber = 0;
}
System.out.println("Thanks for Playing!");
}

while loop not working in Java

I am trying to get this to ask the question over and over again while the user inputs a 'Y'. and stop and return the Event.displayFinalResults(); when the user inputs a 'N'
i am getting a continuous loop right now. I am missing something or my layout it wrong. Any help would be great.
System.out.println("Is there anymore amounts you want to add?(Y/N): ");
Scanner keyboard = new Scanner(System.in);
char choice = keyboard.next().charAt(0);
choice = Character.toUpperCase(choice);
if(choice == 'Y')
{
do
{
System.out.println("Is there anymore amounts you want to add?(Y/N): ");
choice = keyboard.next().charAt(0);
choice = Character.toUpperCase(choice);
readValidateAmountType();
readValidateAmount();
}
while(choice =='Y');
}
else
{
Event.displayFinalResults();
}
thanks again.

You program asks a Yes/No question, then if you answer Yes, it enter a loop which starts by asking the same question again, before asking for the amount value.
You might want to ask for the amount value before asking the Yes/No question again.
If user answer No, the loop will exit (after asking for one more amount value), but Event.displayFinalResults() will not be executed. Drop the else clause, so Event.displayFinalResults() whether it entered the if statement or not.
System.out.println("Is there anymore amounts you want to add?(Y/N): ");
Scanner keyboard = new Scanner(System.in);
char choice = keyboard.next().charAt(0);
choice = Character.toUpperCase(choice);
if (choice == 'Y')
{
do
{
readValidateAmountType();
readValidateAmount();
System.out.println("Is there anymore amounts you want to add?(Y/N): ");
choice = keyboard.next().charAt(0);
choice = Character.toUpperCase(choice);
}
while(choice =='Y');
}
Event.displayFinalResults();

You could do this using break; as follows:
do {
System.out.println("Is there anymore amounts you want to add?(Y/N): ");
choice = keyboard.next().charAt(0);
choice = Character.toUpperCase(choice);
if (choice !='Y') {
break;
}
readValidateAmountType();
readValidateAmount();
} while(true);
Event.displayFinalResults();

One problem I see with this is, your while loop is inside the if statement. Once you exit the while loop, it's NOT going to run the code inside the else block because the if condition was already true.
So try removing the else block. This will make sure the Event.displayFinalResults method is called once the while loop exits.
System.out.println("Is there anymore amounts you want to add?(Y/N): ");
Scanner keyboard = new Scanner(System.in);
char choice = keyboard.next().charAt(0);
choice = Character.toUpperCase(choice);
if(choice == 'Y')
{
do
{
System.out.println("Is there anymore amounts you want to add?(Y/N): ");
choice = keyboard.next().charAt(0);
choice = Character.toUpperCase(choice);
readValidateAmountType();
readValidateAmount();
}
while(choice =='Y');
}
Event.displayFinalResults();

Clear code and compact:
Scanner keyboard = new Scanner(System.in);
char choice;
do {
System.out.println("Is there anymore amounts you want to add?(Y/N): ");
choice = keyboard.next().charAt(0);
choice = Character.toUpperCase(choice);
if(choice == 'Y') {
readValidateAmountType();
readValidateAmount();
}
} while(choice == 'Y');
Event.displayFinalResults();

Try the following out:
public void answering(char answer){
if(answer == 'Y' || answer == 'y'){
System.out.println("Answering");
} else if(answer == 'N' || answer == 'n'){
System.out.println("Not answering");
}
Instead of looping, call this method when you want to ask...

Wrong Quiz result

This is the output of the program
I was able to do till to get this result by doing this program below
import java.util.Scanner;
public class aLittleQuiz {
public static void main(String[] args) {
// declaring varibles
String quizStart;
int quizAns1, quizAns2, quizAns3;
Scanner input = new Scanner(System.in);
System.out.println("Are you ready for a quiz? (y / n)");
quizStart = input.next();
System.out.println("Okay, here it comes!");
// quiz answer 1
System.out.println("\nWhat is the capital of Alaska? \n1) Melbourne\n2) Anchorage\n3) Juneau");
quizAns1 = input.nextInt();
if (quizAns1 == 3) {
System.out.println("That's right");
} else {
System.out.println("Your answer is wrong, sorry!");
}
// quiz answer 2
System.out.println("Q2) Can you store the value ''cat'' in a variable of type int? \n1) yes \n2) no");
quizAns2 = input.nextInt();
if (quizAns2 == 1) {
System.out.println("Sorry, ''cat'' is a string. ints can only store numbers.");
} else if (quizAns2 == 2) {
System.out.println("Correct!");
}
// quiz answer 3
System.out.println("What is the result of 9+6/3? \n1) 5\n2) 11 \n3) 15/3");
quizAns3 = input.nextInt();
if (quizAns3 == 2) {
System.out.println("That's correct!");
} else {
System.out.println("");
}
// if (quizAns == 3 && quizAns == ) {
// }
}
}
but how I can program this part?
"Overall, you got 2 out of 3 correct.
Thanks for playing!"

Declare a variable like int marks and increment it by one inside if\else block(which made for correct answer). And at the end print
System.out.println("Overall, you got" +marks+" out of 3 correct. Thanks for playing!");
Assuming your no of question is fixed( 3 )
String quizStart;
int quizAns1, quizAns2, quizAns3;
int marks=0;
Scanner input = new Scanner(System.in);
System.out.println("Are you ready for a quiz? (y / n)");
quizStart = input.next();
System.out.println("Okay, here it comes!");
// quiz answer 1
System.out.println("\nWhat is the capital of Alaska? \n1) Melbourne\n2) Anchorage\n3) Juneau");
quizAns1 = input.nextInt();
if (quizAns1 == 3) {
System.out.println("That's right");
++marks;
} else {
System.out.println("Your answer is wrong, sorry!");
}
// quiz answer 2
System.out.println("Q2) Can you store the value ''cat'' in a variable of type int? \n1) yes \n2) no");
quizAns2 = input.nextInt();
if (quizAns2 == 1) {
System.out.println("Sorry, ''cat'' is a string. ints can only store numbers.");
} else if (quizAns2 == 2) {
System.out.println("Correct!");
++marks;
}
// quiz answer 3
System.out.println("What is the result of 9+6/3? \n1) 5\n2) 11 \n3) 15/3");
quizAns3 = input.nextInt();
if (quizAns3 == 2) {
System.out.println("That's correct!");
++marks;
} else {
System.out.println("");
}
System.out.println("Overall, you got " +marks+" out of 3 correct. Thanks for playing!");

Looping if statements

Im looking to make this loop after it asks them a question in this case ""What is 2+2?" then taking there input, Then the program should ask "Are you sure Y/N" if they awnser no i want it to go back to the start of this loop and allow them to redo the question. As it is i can't get this to loop and after this part works i will need to do 9 more questions in the same format
import java.util.Scanner;
class Quiz
{
public static void main (String[] args)
{
int q1=0 , q2=0;
boolean correct = false;
char yn1='y';
String q3 , q4;
Scanner input1 = new Scanner( System.in );
int count = 0 ;
//Question 1 start
while (correct == false)
{
System.out.println("What is 2+2? ");
System.out.println("Choices: 0,2,4,8");
q1 = input1.nextInt(); //used after loop
System.out.println("Are You Sure? (y/n)");
char c = input1.next().charAt(0); // Changed LINE
if (c=='y') // Changed LINE
{
if ( q1 == 4) //q1 was stated during loop
System.out.println("You were correct 2+2 = 4");
else
System.out.println("You were wrong");
break;
}
}
//Question 2 start
while (correct == false)
{
System.out.println("how many legs does a legless cow have?");
System.out.println("Choices: 0,25,4,31");
q2 = input1.nextInt();
System.out.println("Are You Sure? (y/n)");
char c = input1.next().charAt(0);
if (c=='y')
{
if ( q2 == 0)
System.out.println("You were correct, the cow has 0 legs");
else
System.out.println("You were wrong");
break;
}
}
//Question 3 start
while (correct == false)
{
System.out.println("What is the capital city of Canada?");
System.out.println("Choices: Toronto, Montreal, Vancouver, Ottawa (capitals count)");
q3 = input1.nextLine();
System.out.println("Are You Sure? (y/n)");
char c = input1.next().charAt(0);
if (c=='y')
{
if ( "Ottawa".equals(q3))
System.out.println("You were correct, The capital is Ottawa");
else
System.out.println("You were wrong");
break;
}
}
}
}
A new problem has occurred i have used the one helpful example and may try to change it to an array later but not in till i get the basics working. all the Questions usings int work so far Ie.
//Question 1 start
while (correct == false)
{
System.out.println("What is 2+2? ");
System.out.println("Choices: 0,2,4,8");
q1 = input1.nextInt(); //used after loop
System.out.println("Are You Sure? (y/n)");
char c = input1.next().charAt(0); // Changed LINE
if (c=='y') // Changed LINE
{
if ( q1 == 4) //q1 was stated during loop
System.out.println("You were correct 2+2 = 4");
else
System.out.println("You were wrong");
break;
}
}
But now i want to use a word awnser so i made a string and put it in instead of int but now instead of allowing input for q3 it skips to input of y/n i don't understand why all of a sudden it would do this yet the other questions work correctly with int.
while (correct == false)
{
System.out.println("What is the capital city of Canada?");
System.out.println("Choices: Toronto, Montreal, Vancouver, Ottawa (capitals count)");
String q3 = input1.nextLine();
System.out.println("Are You Sure? (y/n)");
char c = input1.next().charAt(0);
if (c=='y')
{
if ( "Ottawa".equals(q3))
System.out.println("You were correct, The capital is Ottawa");
else
System.out.println("You were wrong");
break;
}
}
Im sorry if this hasn't been enough detail or is formated wrong and will be sure to fix it if it is.

When reading input, always use q1 = Integer.parseInt(input1.nextLine()); (Even better, use the BufferedReader class). That way, your reading will work smoothly.
Secondly, you can place the if (q1 == 4) within the if (yn1.equals("Y")) statement. If the user has typed "Y" then set correct = true; to proceed to the next question. Further, if the user's answer is correct then increment the counter of right answers else print wrong. So the loop looks like this:
while (correct == false) {
System.out.println("What is 2+2? ");
System.out.println("Choices: 0,2,4,8");
q1 = Integer.parseInt(input1.nextLine());
System.out.println("Are You Sure? (Y/N)");
yn1 = input1.nextLine();
if (yn1.equals("Y")) {
correct = true;
if (q1 == 4) {
System.out.println("You were correct 2+2 = 4");
count++;
} else
System.out.println("You were wrong");
}
}
A few things to look into:
You print "Choices: 0,2,4,8", but nothing stops the user to enter 3 or 3000. Is the choices statement necessary? Then you'll need to check if the user has entered within that range or not also.
Instead of copying & pasting this same loop n times, make use an an array. Have all questions & answers stored in some String array for now. Something like this:
for (int i = 0; i < questions.length; i++) {
boolean nextQ = false;
while (nextQ == false) {
System.out.println(questions[i]);
String ans = input1.nextLine();
System.out.println("Are You Sure? (Y/N)");
yn = input1.nextLine();
if (yn.equalsIgnoreCase("Y")) {
nextQ = true;
if (ans.equals(answers[i])) {
System.out.println("You were correct " + questions[i]
+ " = " + answers[i]);
count++;
} else
System.out.println("You were wrong");
}
}
}
I changed the boolean variable correct to nextQ to avoid confusion. Hope the sets you in the right direction.

I tried to compile your program.But I am getting some errors:-
error: variable q1 might not have been initialized
According to what I understand from ur question.Here is the program u want:-
import java.util.Scanner;
class stack1
{
public static void main (String[] args)
{
int q1=0 , q2 , q3, q4, q5, q6 , q7 ,q8 ,q9 ,q10 , a ;
boolean correct = false;
char yn1='Y';
Scanner input1 = new Scanner( System.in );
int count = 0 ;
while (correct == false)
{
System.out.println("What is 2+2? ");
System.out.println("Choices: 0,2,4,8");
q1 = input1.nextInt(); //used after loop
System.out.println("Are You Sure? (Y/N)");
char c = input1.next().charAt(0); // Changed LINE
if (c=='y') // Changed LINE
{
System.out.println("Exiting the program");
correct = true; //It should now stop the loop and carry on
break;
}
}
if ( q1 == 4) //q1 was stated during loop
System.out.println("You were correct 2+2 = 4");
else
System.out.println("You were wrong");
//Soon will add int score and add 1 each time its correct
// will be using 9 more loops the exact same way
}
}
I have mentioned all the changed lines with comment '//changed line' .

This is the answer for the edited Question:-
import java.util.Scanner;
class stack2
{
public static void main (String[] args)
{
int q1=0 , q2 , q3, q4, q5, q6 , q7 ,q8 ,q9 ,q10 , a ;
boolean correct = false;
char yn1='Y';
String s="";
System.out.println(s);
Scanner input1 = new Scanner( System.in );
int count = 0 ;
while (correct == false)
{
System.out.println("What is the capital city of Canada?");
System.out.println("Choices: Toronto, Montreal, Vancouver, Ottawa (capitals count)");
s = input1.nextLine();
System.out.println(s);
System.out.println("Are You Sure? (Y/N)");
char c = input1.next().charAt(0); // Changed LINE
if (c=='y') // Changed LINE
{
System.out.println("Exiting the program");
correct = true; //It should now stop the loop and carry on
break;
}
if (s.equals("Ottawa")) //q1 was stated during loop
System.out.println("You were correct, The capital is Ottawa");
else
System.out.println("You were wrong");
}
//Soon will add int score and add 1 each time its correct
// will be using 9 more loops the exact same way
}
}
Be careful while entering the input.It shoul be exactly "Ottawa". Best of luck