Java Scanner.nextLine() not waiting for input
<p>I have several methods that I've used previously to accept user input and return it as a certain data type to the method that calls for it.  I have used these methods, or variations of them, in previous projects.</p>

<p>I've adopted the method that I used for string to select the first char given and return that, so that I can use this in a menu.  Every time I start the application, the main menu appears and waits for user input.  After receiving this input, the program loops continuously until stopped.  Here is my method for capturing the char:</p>

<pre><code>private char getUserChar(String prompt) {
    try {
        Scanner scan = new Scanner(System.in);
        System.out.print(prompt);
        String tempString = "";
        tempString = scan.nextLine();
        scan.close();
        char userChar = tempString.charAt(0);
        return userChar;
    } catch(Exception ex) {
        System.out.println(ex.getMessage());
    }
    return 0;
}
</code></pre>

<p>The code loops due to the try/catch block, as scan.nextLine() never waits for the next input.  Without it, the exception is typically related to not finding a new line.  I've tried the while(scan.hasNextLine()) that seems to work for other people; however, once the time for input arrives, it never breaks out of the loop.  I also don't believe I'm tripping up on the nextInt() issue that everyone seems to have troubles with. I'll post the code for the entire class below:</p>

<pre><code>import java.util.Scanner;
import controller.Controller;
public class TUI {
    private Controller controller;
    public TUI() {
        Controller controller = new Controller();
        this.controller = controller;
    }

    public void run() {
        boolean wantToQuit = false;
        char userInput = 0;
        System.out.println("Welcome to the Mart.");
        do{
            userInput = mainMenu();
            if(isUserInputValid(userInput))
                switch(userInput){
                    case 'a': addItem();
                    break;
                    case 'r': controller.removeItem();
                    break;
                    case 'i': controller.printInventory();
                    break;
                    case 'p': controller.customerPurchase();
                    break;
                    case 'w': controller.weeklyStock();
                    break;
                    case 'c': wantToQuit = true;
                    break;
                }
            else System.out.println("\nMainMenu");



        } while(!(wantToQuit));
        System.out.println("WolfMart is now closed.  Thank you and good-bye.");
    }




    private boolean isUserInputValid(char userInput) {
        char[] testSet = {'a', 'r', 'i', 'p', 'c', 'w'};
        for(char currentChar : testSet) {
            if(currentChar == userInput)
                return true;
        }
        return false;
    }

    private char mainMenu() {
        System.out.println();
        controller.printInventory();
        String mainMenuSelection = "What would you like to do: (a)dd item, (r)emove item, print (i)nventory, " +
            "(p)urchase by customer, (c)lose store?\r\n";

        char mainMenuInput = getUserChar(mainMenuSelection);
        return mainMenuInput;
    }

    private char getUserChar(String prompt) {
        try {
            Scanner scan = new Scanner(System.in);
            System.out.print(prompt);
            String tempString = "";
            tempString = scan.nextLine();
            scan.close();
            char userChar = tempString.charAt(0);
            return userChar;
        } catch(Exception ex) {
            System.out.println(ex.getMessage());
        }
        return 0;
    }


    private int getUserInt(String prompt) {
        Scanner scan = new Scanner(System.in);
        int userInt = -1;
        try {
            System.out.print(prompt);
            String input = scan.nextLine();
            userInt = Integer.parseInt(input);
        }
        catch(NumberFormatException nfe) {
            System.out.println("I did not recognize your command, please try again.");
        }
        scan.close();
        return userInt;
    }

    private String getUserString(String prompt) {
        Scanner scan = new Scanner(System.in);
        String userString = null;
        try{
            System.out.print(prompt);
            userString = scan.nextLine();
        } catch(Exception ex)
        {
            System.out.println("I did not recognize your command, please try again.");
        }
        scan.close();
        return userString;
    }

    private double getUserDouble(String prompt) {
        Scanner scan = new Scanner(System.in);
        double userDouble = -1.0;
        try {
            System.out.print(prompt);
            String input = scan.nextLine();
            userDouble = Double.parseDouble(input);
        }
        catch(NumberFormatException nfe) {
            System.out.println("I did not recognize your command, please try again.");
        }
        scan.close();
        return userDouble;
    }

    private void addItem() {
        String itemName = "";
        double price;
        int quantity;
        String namePrompt = "Enter the name of the item being added to the inventory: ";
        String pricePrompt = "Enter the cost of " + itemName + ": ";
        String quantityPrompt = "Enter the quantity of " + itemName + ": ";
        itemName = getUserString(namePrompt);
        price = getUserDouble(pricePrompt);
        quantity = getUserInt(quantityPrompt);
        controller.addItem(itemName, quantity, price);
    }




}
</code></pre>
