Problems with try/catch java

Question

I am having trouble using this try/catch statement. I am trying to use it to throw an error message that says, "Please enter an integer!" if the user enters a letter. The first one I used worked, but it ends up taking 2 lines of user input rather than just one, so it essentially skips over a question that was supposed to be asked. After that, none of the other ones work at all, they just get completely skipped. I also need to do the same thing for user input where if a user enters an integer where a letter should be, it throws an error message that says "Please enter a string!". I know I am pretty close!

public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        boolean validInput = false;
        int val = 0;


        System.out.print("Enter your first name: ");    
        String firstName = input.nextLine();
        System.out.print("Enter your last name: ");
        String lastName = input.nextLine();
        System.out.print("Enter your address: ");
        String address = input.nextLine();
        System.out.print("Enter your city: ");
        String city = input.nextLine();
        System.out.print("Enter your state: ");
        String state = input.nextLine();
        System.out.print("Enter your zip code + 4: ");
        String zip = input.nextLine();
        while(!validInput) {
             try {
        val = input.nextInt();
        validInput = true;
           } catch(Exception e) {
        System.out.println("Please enter an integer!");
        input.nextLine();
    }
}
        System.out.print("Enter amount owed: ");
        String amount = input.nextLine();
        while(!validInput) {
             try {
        val = input.nextInt();
        validInput = true;
           } catch(Exception e) {
        System.out.println("Please enter an integer!");
        input.next();
    }
}
        System.out.print("Enter your payment amount: ");
        String payment = input.nextLine();
        while(!validInput) {
             try {
        val = input.nextInt();
        validInput = true;
           } catch(Exception e) {
        System.out.println("Please enter an integer!");
        input.next();
    }
}
        System.out.print("Enter the date of payment: ");
        String date = input.nextLine();
        while(!validInput) {
             try {
        val = input.nextInt();
        validInput = true;
           } catch(Exception e) {
        System.out.println("Please enter an integer!");
        input.next();
    }
}
        System.out.println("\t\t\t\t\t" + "XYZ Hospital");
        System.out.println();
        System.out.println("Name Information" + "\t\t\t\t" + "Address" + "\t\t\t\t\t\t" + "Payment");
        System.out.println();
        System.out.println("Last" +"\t"+ "First" + "\t\t\t" + "Address Line 1" + "\t" + "City" + "\t" + "State" + "\t" + "Zip" + "\t" + "Amount Owed" + "\t" + "Payment Amount" + "\t" + "Payment Date");
        System.out.println();
        System.out.println(lastName + " " + firstName + "\t" + address + " " + city + ", " + state + " " + zip + "\t" + amount + "\t\t" + payment +"\t\t"+ date);
        System.out.print("Would you like to enter abother patient? Type Yes or No: ");
        String userInput = input.nextLine();
        if (userInput.equals("Yes")) {
            while (userInput.equals("Yes")) {
                System.out.print("Enter your first name: ");    
                String firstName2 = input.nextLine();
                System.out.print("Enter your last name: ");
                String lastName2 = input.nextLine();
                System.out.print("Enter your address: ");
                String address2 = input.nextLine();
                System.out.print("Enter your city: ");
                String city2 = input.nextLine();
                System.out.print("Enter your state: ");
                String state2 = input.nextLine();
                System.out.print("Enter your zip code + 4: ");
                String zip2 = input.nextLine();
                System.out.print("Enter amount owed: ");
                String amount2 = input.nextLine();
                System.out.print("Enter your payment amount: ");
                String payment2 = input.nextLine();
                System.out.print("Enter the date of payment: ");
                String date2 = input.nextLine();
                System.out.println("\t\t\t\t\t" + "XYZ Hospital");
                System.out.println();
                System.out.println("Name Information" + "\t\t\t\t" + "Address" + "\t\t\t\t\t\t" + "Payment");
                System.out.println();
                System.out.println("Last" +"\t"+ "First" + "\t\t\t" + "Address Line 1" + "\t" + "City" + "\t" + "State" + "\t" + "Zip" + "\t" + "Amount Owed" + "\t" + "Payment Amount" + "\t" + "Payment Date");
                System.out.println();
                System.out.println(lastName2 + " " + firstName2 + "\t" + address2 + " " + city2 + ", " + state2 + " " + zip2 + "\t" + amount2 + "\t\t" + payment2 +"\t\t"+ date2);
                System.out.print("Would you like to enter another patient? Type Yes or No: ");
                userInput = input.nextLine();
            }

        }
        else if (userInput.equals("No")) {
            System.out.println("Goodbye");
        }

Answer 1

A quick solution maybe, I've used Scanner.hasNextInt to check what the next token is before getting required ints:

import java.util.Scanner;

public class java_so {
    private static int privateGetInt(String request, Scanner input) {
        // cant be false, but we return when done.
        while (true) {
            // print the question
            System.out.println(request);
            // check what the next token is, if an int we can then retrieve
            if (input.hasNextInt() == true) {
                int out = input.nextInt();
                input.nextLine(); // clear line, as nextInt is token orientated, not line,
                return out;
            } else {
                // else for when not an int, clear line and try again
                input.nextLine();
            }
        }
    }

    public static void main(String[] args) {
            Scanner input = new Scanner(System.in);

            System.out.print("Enter your first name: ");    
            System.out.println(input.nextLine());
            // call function above 
            System.out.println(privateGetInt("enter an Int", input));
            System.out.print("Enter your last name: ");
            System.out.println(input.nextLine());
            System.out.print("Enter your address: ");
            System.out.println(input.nextLine());
    }
}

It seems a bit like the problem may have been after a call to input.nextInt you haven't got rid of the rest of the line (which is probably just "\n") so the next call to input.getLine() only gets that, jumping on one. Following input.getInt with input.getLine clears this.

Answer 2

You should take input in catch block comment input.nextLine() in catch block then it should work properly

I have added explanation in the code itself

public static void main(String[] args) {
  Scanner input = new Scanner(System.in);
  boolean validInput = false;
  int val = 0;

  System.out.print("Enter your first name: ");
  String firstName = input.nextLine();
  System.out.print("Enter your last name: ");
  String lastName = input.nextLine();
  System.out.print("Enter your address: ");
  String address = input.nextLine();
  System.out.print("Enter your city: ");
  String city = input.nextLine();
  System.out.print("Enter your state: ");
  String state = input.nextLine();
  System.out.print("Enter your zip code + 4: ");
  String zip = input.nextLine();
  while (!validInput) {
    try {
      val = input.nextInt();
      validInput = true; //if exception occurs this line wont be executed
    } catch (Exception e) {
      System.out.println("Please enter an integer!");
      // input.nextLine(); --remove this line
    }
  }
  System.out.print("Enter amount owed: ");
  String amount = input.nextLine();
  //reset the value of validInput
  //validInput will true after the execution of above while loop
  validInput = false;
  while (!validInput) {
    try {
      val = input.nextInt();
      validInput = true; //if exception occurs this line wont be executed
    } catch (Exception e) {
      System.out.println("Please enter an integer!");
      // input.next(); -- remove this line
    }
  }
}

Answer 3

You don't reset validInput to False after your first while loop. So it doesn't enter the next.