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Where should I put the while loop/boolean?

I made a method should pull up a menu with a list of actions, allows users to choose an action, execute the action, then goes back to the menu and repeats until the user chooses to end the session. I'm currently at a bit lost on what to do with the while loop and the boolean endSession(), which I've been shuffling around in the code that sometimes lets me compile it and never does what I want it to do. The place I currently have it causes it to not only skip the action, but loop infinitely. I don't really need to know what's exactly wrong, I just want to know where to put the while loop/boolean endSession (and although not necessary, an explaination for why the answer works would be nice).
//package bookStoreLab;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Scanner;
public class BookStoreDriver {
private static final int PRINT_INVENTORY=1;
private static final int SEARCH_TITLE=2;
private static final int SEARCH_AUTHOR=3;
private static final int AVAILABLE_BOOKS=4;
private static final int NEW_RELEASES=5;
private static final int PURCHASE=6;
private static final int ADD_INVENTORY=7;
//include rest of constants here for all choices
private static Scanner keyboard;
public static void main(String[] arg) throws IOException, FileNotFoundException{
System.out.println("\f");
keyboard = new Scanner(System.in);
BookStore booky = new BookStore();
System.out.println("*****" +
"Welcome To Your Local Book Store!" + "*****");
booky.inputBooks();
boolean endSession = false;
int choice = getChoice(endSession);
if(choice==0){
endSession = true;
}
if(choice==PRINT_INVENTORY){
booky.printInventory();
}
if(choice==SEARCH_TITLE){
booky.searchByTitle();
}
if(choice==SEARCH_AUTHOR){
booky.searchByAuthor();
}
if(choice==AVAILABLE_BOOKS){
booky.printAvailableBooks();
}
if(choice==NEW_RELEASES){
booky.printNewReleases();
}
if(choice==PURCHASE){
booky.purchase();
}
if(choice==ADD_INVENTORY){
booky.addToInventory();
}
else{
System.out.println("Please choose an option that's actually listed.");
}
printFarewell();
}
public static int getChoice(boolean a){
int choice=-1;
while(!a){
System.out.println("\n\nWhat store service would you like" +
"to perform? (Enter 0-7)");
System.out.println("\t0. Enter 0 to end your session");
System.out.println("\t1. View all books");
System.out.println("\t2. Search by title");
System.out.println("\t3. Search by author");
System.out.println("\t4. View available books for purchase");
System.out.println("\t5. View new releases");
System.out.println("\t6. Purchase one or more copies of a book");
System.out.println("\t7. Add book(s) to inventory");
System.out.println("Enter your choice: ");
choice = keyboard.nextInt();
}
return choice;
}
public static void printFarewell(){
System.out.println("\n\nThank you for using the system!");
}
}
So far I've tried:
-getting rid of parameter a for getChoice() and moving the while loop to before if(choice==0) and ended it at the else statement
while(!endSession){
if(choice==0){
endSession = true;
}
if(choice==PRINT_INVENTORY){
booky.printInventory();
}
if(choice==SEARCH_TITLE){
booky.searchByTitle();
}
if(choice==SEARCH_AUTHOR){
booky.searchByAuthor();
}
if(choice==AVAILABLE_BOOKS){
booky.printAvailableBooks();
}
if(choice==NEW_RELEASES){
booky.printNewReleases();
}
if(choice==PURCHASE){
booky.purchase();
}
if(choice==ADD_INVENTORY){
booky.addToInventory();
}
else{
System.out.println("Please choose an option that's actually listed.");
}
}
which resulted in the action looping infinitely (for example: repeatly doing printInventory() until I forced the console to stop).
-moving the boolean endSession to inside getChoice() (no parameters), which almost works, except for the part where it skips doing the action (for example: entering 1, and the menu immediately popping back up without doing printInventory()).

Put the while loop in the main method. Your boolean value never changes inside your method, so your while loop will either run 0 times or infinite times.
Let your helper method collect a single input, and let the loop in your main method inspect the last returned value and determine whether to execute another iteration of the loop.
public static void main(String[] args) {
int choice = getChoice();
while(choice != 0) {
choice = getChoice();
}
}
public static int getChoice() {
// display menu
// collect user input
// return user input
}

1) get rid of the parameters,
2) put the while loop before int choice = getChoice(),
3) end it after the else loop.
I have no idea why that works but I'm too tired to care so yeet!

How would I get a String from another class?

import java.util.*;
class Player {
public static void main (String [] args) {
String number = Text.nextLine
}
}
I want the user input from this class and
bring into another class and use the number variable for a
If statement

I want the user input from this class and bring into another class and
use the number variable for a If statement.
It is simple take a look at below example(make sure to add both classes in one package different java files as Player.java and ExampleClass.java),
This is the class that Scanner has:
import java.util.*;
public class Player{
public static void main (String [] args){
Scanner getInput = new Scanner(System.in);
System.out.print("Input a number");
//you can take input as integer if you want integer value by nextInt()
String number = getInput.nextLine();
ExampleClass obj = new ExampleClass(number);
obj.checkMethod();
}
}
This is the class that check number:
public class ExampleClass{
int number;
public ExampleClass(String number){
try{
//If you want to convert into int
this.number = Integer.parseInt(number);
}catch(NumberFormatException e){
System.out.println("Wrong input");
}
}
public void checkMethod(){
if(number > 5){
System.out.println("Number is greater.");
}else{
System.out.println("Number is lesser.");
}
}
}
Few thing to mention:
Your example code contains syntax errors, fix those first.
If you want integer you can use getInput.nextInt() rather than
getInput.nextLine().
You can create getter and setters to set vaues and get values. In my example I just only set value through the constructor.
Use proper naming convention.
In my example I convert the String into integer inside the constructor and wrap with try-catch block to prevent from NumberFormatException(If you input character or something you can see wrong input will print). Sometimes in variaus situation it is not good to use try-catch in constructor. To learn more about this, please read Try / Catch in Constructor - Recommended Practice.

Where you normally make an import on the other class, just import the Player class and it should work

I'm not sure if I got it, I suppose you're using a scanner.
This is the way I would do that:
Scanner class:
public class ScannerTest {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
while (true) {
System.out.println("Insert a decimal:");
String inputValue = scanner.nextLine();
if(!new ScannerCalc().isNumeric(inputValue)){
System.out.println("it's not a number...");
break;
}
else
new ScannerCalc().checkNumber(inputValue);
}
}
}
ScannerCalc class:
public class ScannerCalc {
public boolean isNumeric(String s) {
return s != null && s.matches("[-+]?\\d*\\.?\\d+");
}
public void checkNumber(String number){
if(Integer.parseInt(number)%2==0)
System.out.println("it' even");
else
System.out.println("it's odd");
}
}
Pay attention on instantiation of classes to reuse methods.

If you want to make use of a local variable in another entity, it is better to pass it as an argument to a method of the other entity. For example
OtherClass.operation(scanner.nextLine()); // In case method is static
new OtherClass().operation(scanner.nextLine()); // In case method is not static

Creating a Java Method

I am creating a java program that runs in tie with another file to help create what is called Object oriented programming.
So I have the whole program completed but I am having a hard time understanding how to make it compile and run. I know my problem is within the name of the method. However I dont quiet understand how to know what to call the method. From what I read there is several different types you can call it.
(Also I know the indentation looks messed up, it's right in my actual program)
Here is what I am looking at to help make sense of my question:
import java.util.Scanner;
import java.util.Random;
public class RockPaperScissors
{
public static void main(String[] args)
{
class getUserChoice
{
System.out.println("Would you you like to play rock, paper scissors?");
userChoice = in.nextLine();
while (!userChoice.equalsIgnoreCase("Rock") && !userChoice.equalsIgnoreCase("Paper") && !userChoice.equalsIgnoreCase("Scissors"))
{
System.out.println("Invalid entry please try again");
userChoice = in.nextLine();
}
userChoice = userChoice.toUpperCase();
return userChoice;
} //end of UserChoice
class getCPUChoice
{
computerRandom = r.nextInt(3)+1;
if (computerRandom == 1) cpuChoice = "Rock";
else if (computerRandom == 2) cpuChoice = "Paper";
else if (computerRandom == 3) cpuChoice = "Scissors";
}
class pickWinner
{
//tie
if (userChoice.equals(cpuChoice))
{
winner = tie;
}
//user has rock
if (userPlay.equals("rock"))
{
if (cpuChoice.equals("Scissor"))
{
winner = user;
}
else if (cpuChoice.equals("Paper"))
{
winner = Computer;
}
else if (cpuChoice.equals("Rock"))
{
winner = tie;
}
}
if (userPlay.equals("Paper"))
{
if (cpuChoice.equals("Scissor"))
{
winner = Computer;
}
else if (cpuChoice.equals("Paper")
{
winner = tie;
}
else if (cpuChoice.equals("Rock")
{
winner = user;
}
}
if (userPlay.equals("Scissors"))
{
if (cpuChoice.equals("Scissor"))
{
winner = tie;
}
else if (cpuChoice.equals("Paper")
{
winner = user;
}
else if (cpuChoice.equals("Rock")
{
winner = computer;
}
}
}
}//end of RockPaperScissors
}
My error I get is:
RockPaperScissors.java:10: error: expected
System.out.println("Would you you like to play rock, paper scissors?");
Which from what I understand is from not having the class setup up right. Could someone maybe help explain how you know what to name each method correctly?
Thanks!

You can't declare more than one public class in a file
To fix the problem, remove the word public.
However I dont quiet understand how to know what to call the method.
As for this, to call a method, simply use the method name (full example of my answer):
public static void main(String[] args) {
class something{
public void someMethod(int argument){
//this doesn't do anything
}
}
something s = new something();
s.someMethod(1);
}

This isn't valid Java. You don't create a class to get choices; make it a method.
public class RockPaperScissors {
private static final String [] choices = { "ROCK", "PAPER", "SCISSORS" };
private Random random;
public RockPaperScissors() { this(null); }
public RockPaperScissors(Long seed) {
this.random = (seed == null) ? new Random() : new Random(seed.longValue());
}
// An Enum would be better than a number or String
public String nextChoice() {
return choices[this.random.nextInt(choices.length)];
}
}

Classes and methods can be defined inside other classes, but neither can be defined inside methods (functions), with the exception of anonymous functions. If this is a standalone program you intended to write, and you intended for getUserChoice and getCPUChoice to be methods, just remove the class keyword before both names and perhaps replace them with static if you want them to be static methods of your RockPaperScissors class. Methods need to have a return type and in your case, it can be String. You would still need to invoke either method in your main method.

I would imagine this is the sort of structure you are looking for in a "standard" program. You can declare other classes in other files and import those too. Your code will generally run in methods within those classes and is all called from the main method which is your entry point.
//imports here
public class ClassName {
public static void main(String[] args) {
//main entry point to your program
}
private String methodName(String param1) {
//do some stuff here
return someValue;
}
}

You can't create several classes in a single file. So it should have only one "class" keyword here.
Your methods are not well formatted, you should take a look at the Java Oracle Tutorial to get started with Java :)
Here is a simple example of class + method :
public class MyClass{
//Attribute
public int myMethod(int x) {
return x+1;
}
}
A method is defined by its visibility (public), the returned type (int), its name (myMethod) and its parameters (int x). So here your methods have a "class" returned type, which is not possible.

It seems like you are trying to write some kind of a guess game between a user and a computer...nice but less easier than it sounds.
As many have said you are having trouble because you are declaring classes with a wrong visibility and not exactly at the right place
The names you gave your two classes gives me the feeling they should be methods rather than classes. So It would be simpler two have three methods.
The main method: that's where you run your game loop
A getUserChoice(): that's where you ask the user to input its choice (Good that you block the user until he inputs a valid choice)
The getCPUChoice: That's where you ask the cpu to input his choice
Some one the variables you use will necessarily be shared between more than one method, so declare them at the class level so that they can be accessible wherever necessary. For example:
public class RockPaperScissors {
static String userChoice = "";
static String cpuChoice = "";
static Scanner in = new Scanner(System.in);
static Random r = new Random();
// ... rest of the code here
You should instantiate your Random object and declare your computerRandom variable before using them.
Just as a practical illustration I created a game loop (there are often infinite :)) in the main method where I receive the user's input and the computer input and then compare then. Success comes with a congratulation and failure with a try again note. I am not assuming that it is exactly where you were trying to get, but it could be.
Here is my complete illustration code
import java.util.Scanner;
import java.util.Random;
/**
* Created by alompo on 07.11.16.
*/
public class RockPaperScissors {
static String userChoice = "";
static String cpuChoice = "";
static Scanner in = new Scanner(System.in);
static Random r = new Random();
public static void main(String[] args) {
while(true) {
getUserChoice();
getCPUChoice();
if (cpuChoice.equalsIgnoreCase(userChoice)) {
System.out.println("Good choice, you have a match with the computer");
} else {
System.out.println("Sorry mismatch between you and the computer...try again");
}
}
}
public static void getUserChoice()
{
System.out.println("Would you you like to play rock, paper scissors?");
userChoice = in.nextLine();
while (!userChoice.equalsIgnoreCase("Rock") && !userChoice.equalsIgnoreCase("Paper") && !userChoice.equalsIgnoreCase("Scissors"))
{
System.out.println("Invalid entry please try again");
userChoice = in.nextLine();
}
} //end
public static void getCPUChoice()
{
int computerRandom = r.nextInt(3)+1;
if (computerRandom == 1) cpuChoice = "Rock";
else if (computerRandom == 2) cpuChoice = "Paper";
else if (computerRandom == 3) cpuChoice = "Scissors";
}
}

Instance variable with the same value for different objects although different values were assigned

First of all and before posting my question let me ask you people to stop downvoting my questions even if they seem stupid to you ,this site is an important place for me, it helps me a lot with my java doubts which are many,a question ban would be an heavy setback for me, so be helpful even by not answering!
Now for the question,
I have this method were i assign a value to a setter method with user input
public void addName() {
Scanner input = new Scanner(System.in);
System.out.println("Do you want to add a citizen name?");
String answer = input.nextLine();
while (!answer.equals("y") || (!answer.equals("n"))) {
if (answer.equals("y")) {
String giveName = input.nextLine();
this.setName(giveName);
break;
} else if (answer.equals("n")) {
System.out.println("Not adding a name!");
break;
}else{System.out.println("Please choose y or n!");
answer = input.nextLine();}
}
}
this method is later called in main from object p1 and object p2 and being assigned a differend value for each one to the instance variable name
import java.util.ArrayList;
import java.util.Scanner;
public class MainClass {
public static void main(String[] args) {
ArrayList<Pessoas> lista = new ArrayList<Pessoas>();
Pessoas p1 = new Portugueses();
Pessoas p2 = new Alemaes();
p1.addName();
p2.addName();
System.out.println(p1.getName());
System.out.println(p2.getName());
}
}
but when i call the getName() method at the end of main both p1 and p2 have the same value!
Shouldn't each object get it´s own copy of an instance variable?

The Problem is in your addName()-function. Your running your loop(while (!answer.equals("y") || (!answer.equals("n")))) until a y or n is entered. So as soon as you enter it, your loop will stop.
In your loop your checking if the input that was made cotains a y or n. Now the problem should be clear. Your loop won't run with those two values entered, but inside the loop you want to check if one of those is entered.
Two little personal hints(everyone has another style): Don't use break; let your loops end themselfs. Do it with an boolean-variable and updating it's state.
The second hint would be to use one Scanner-Object. For example you could add a Scanner-parameter to your addName-function. Just init one in your MainClass.
Those hints and fixes of the problem applied to your code could look like that:
public void addName(Scanner input) {
System.out.println("Do you want to add a citizen name?");
String answer;
boolean isAnotherInputNeeded = true;
while (isAnotherInputNeeded) {
answer = input.nextLine();
if (answer.equals("y"))
{
System.out.println("What's the name?");
String giveName = input.nextLine();
this.setName(giveName);
isAnotherInputNeeded= false;
}
else if (answer.equals("n"))
{
System.out.println("Not adding a name!");
this.setName("No name entered");
isAnotherInputNeeded= false;;
}
else
{
System.out.println("Please choose y or n!");
}
input.reset();
}
}
And your MainClass:
import java.util.ArrayList;
import java.util.Scanner;
public class MainClass {
public static void main(String[] args) {
ArrayList<Pessoas> lista = new ArrayList<Pessoas>();
Pessoas p1 = new Pessoas();
Pessoas p2 = new Pessoas();
Scanner input = new Scanner(System.in);
p1.addName(input);
p2.addName(input);
System.out.println("You entered the following names:");
System.out.println(p1.getName());
System.out.println(p2.getName());
}
}
Hope that helps!

Cannot make Scanner String method work

I'm trying to create a Scanner method for strings that returns the value entered by the user only if it is not blank (whitespace, user hitting 'enter' immediately etc..). If the user does this I want to print out an error message and have the loop return to the beginning again and await a new user input. If correct, I want the method to return the correct input value.
My code is as such:
private static final Scanner scr = new Scanner(System.in);
private static String readString(){
while(true){
String command = scr.next();
if(command != null && !command.trim().isEmpty()){
return command;
}
System.out.println("You have to type something");
}
}
Right now when I run this method in other methods if I leave a blank or simply hit 'enter' my output simply leaves a blank space until I type a string such as 'abc'. Then it returns that value.
Any helpful advice is appreciated!

Replace src.next() with src.nextLine()
private static final Scanner scr = new Scanner(System.in);
public static void main(String[] args) {
System.out.println(readString());
}
private static String readString() {
while (true) {
String command = scr.nextLine();
if (command != null && !command.trim().isEmpty()) {
return command;
}
System.out.println("You have to type something");
}
}