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Thread: Catch without a try error

  1. #1
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    Default Catch without a try error

    I'm doing a project where I have to catch a user inputting a string into one of the prompt.
    Problem is it seems I always get catch without a try error no matter what I do.
    it keeps saying expected ";" on the catch statement... which is incorrect.
    error(s) are appearing at line 49 - try without a catch.
    Line 102 - catch without a try.
    line 92 - while statement is unreachable.
    and line 107 which is a bracket it says " class, or enum expected".
    I couldn't tell you what I did fix because my original code was something completely different so I restarted a few things to fix certain problems that could occur.
    I've looked around the internet found bad examples to try to fix my code with myself.

    //This is a program that will calculate a monthly payment and loop it. If user gives bad data you will be prompted.
     
    package monthypayment2;
    import java.text.NumberFormat;
    import java.util.Scanner;
     
     
    public class Monthypayment2 {
        private static double monthlypay1;
        private static String choice;
        private static boolean n;
        private static String False;
        private static boolean y;
     
     
     
        /**
         * @param args the command line arguments
         */
        public static void main(String[] args) {
            Scanner in = new Scanner(System.in);
     
            //format number and currency
           NumberFormat NF = NumberFormat.getCurrencyInstance();
     
     
            double months;
            double numyears;
            double loanamount;
            double rate;
            double monthlypay1;
            String choice = "y";
            double calc1;
            double calc2;
            double calc3;
            double calc4;
     
     
     
     
          while (choice.equals("y")) {
     
    try {
            //prompt loan amount
            loanamount=0;
            rate = 0;
            numyears = 0;
     
     
            System.out.print("Enter Loan Amount:");                           
            loanamount = Double.parseDouble(in.nextLine());
     
            //prompt rate
            System.out.print("Enter Rate:");
             rate = Double.parseDouble(in.nextLine());
     
     
             //prompt years
            System.out.print("Enter Number of Years:");
            numyears = Double.parseDouble(in.nextLine());
     
            rate = rate / 12 / 100;
            months = 12 * numyears;
     
     
          //calculation monthly
            calc1 = loanamount * rate;
            calc2 = (Math.pow (1 + rate, months));
            calc3 = (calc2 -1);
            calc4 = (calc2 / calc3);
     
            monthlypay1 = loanamount * rate * calc4;
     
     
     
             if ((loanamount > 0 && rate > 0) && numyears > 0 ) {
                System.out.println("The Monthly Payment is:" + NF.format (monthlypay1));  
                } else { 
                 System.out.println("You need to enter positive numerical data!");
     
             }
                break;
     
    }
     
            while (monthlypay1 < 0) {
                System.out.print("You need to enter positive numerical data!");
                break;
     
     
             }
                System.out.print("");
                System.out.print("Would you like to continue calculations( y / n)?");
     
                choice  = in.nextLine();
     
     
               catch (Exception e) {
                   }
           }
        }
    }


  2. #2
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    Default Re: Catch without a try error

    You need to have a try block before the catch. The try block is where an exception might occur and the catch blocks tell what to do if certain exceptions occur.

    You only have a catch block. You need both a try and a catch block or else you will get a compiler error.

    There can't be any code between the try and the catch blocks.

    It's similar to what happens if you don't have brackets and have an if/statement with more than one line of code after the if and before the else.

  3. #3
    Super Moderator Norm's Avatar
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    Default Re: Catch without a try error

    If you don't understand my answer, don't ignore it, ask a question.

  4. The Following User Says Thank You to Norm For This Useful Post:

    Ancharius (October 29th, 2013)

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    Default Re: Catch without a try error

    Thanks alot guys. I will look at the tutorial. And My java teacher told me to put everything within the try block to make it more simple. Because it will try through everything and catch any error at the end.

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    Default Re: Catch without a try error

    That is the simplest solution. As you get more experienced you should only place code that can throw an exception inside the try block.
    Improving the world one idiot at a time!

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    Default Re: Catch without a try error

    Ok i fixed the error's of catch without a try and vice versa. But now its telling me that my variable "monthlypay1" is not initialized which I don't understand how it isn't. Otherwise the code wouldn't work at the beginning...
    The error is occurring at the last while statement.
    package monthypayment2;
    import java.text.NumberFormat;
    import java.util.Scanner;
     
     
    public class Monthypayment2 {
        private static double monthlypay1;
        private static String choice;
        private static boolean n;
        private static String False;
        private static boolean y;
     
     
     
        /**
         * @param args the command line arguments
         */
        public static void main(String[] args) {
            Scanner in = new Scanner(System.in);
     
            //format number and currency
           NumberFormat NF = NumberFormat.getCurrencyInstance();
     
     
            double months;
            double numyears;
            double loanamount;
            double rate;
            double monthlypay1;
            String choice = "y";
            double calc1;
            double calc2;
            double calc3;
            double calc4;
     
     
     
     
          while (choice.equals("y")) {
     
     try {
            //prompt loan amount
            loanamount=0;
            rate = 0;
            numyears = 0;
     
     
            System.out.print("Enter Loan Amount:");                           
            loanamount = Double.parseDouble(in.nextLine());
     
            //prompt rate
            System.out.print("Enter Rate:");
             rate = Double.parseDouble(in.nextLine());
     
     
             //prompt years
            System.out.print("Enter Number of Years:");
            numyears = Double.parseDouble(in.nextLine());
     
            rate = rate / 12 / 100;
            months = 12 * numyears;
     
     
          //calculation monthly
            calc1 = loanamount * rate;
            calc2 = (Math.pow (1 + rate, months));
            calc3 = (calc2 -1);
            calc4 = (calc2 / calc3);
     
            monthlypay1 = loanamount * rate * calc4;
     
     
     
             if ((loanamount > 0 && rate > 0) && numyears > 0 ) {
                System.out.println("The Monthly Payment is:" + NF.format (monthlypay1));  
                } else { 
                 System.out.println("You need to enter positive numerical data!");
     
             }
                break;
     
           } catch (Exception e ) {
           }
     
           [B] while (monthlypay1 < 0) [/B]{
                System.out.print("You need to enter positive numerical data!");
                break;
     
     
             }
                System.out.print("");
                System.out.print("Would you like to continue calculations( y / n)?");
     
                choice  = in.nextLine();
     
     
        }
    }
    }

  8. #7
    Super Moderator Norm's Avatar
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    Default Re: Catch without a try error

    my variable "monthlypay1" is not initialized
    Which one? I see two variables with that name.
    If you don't understand my answer, don't ignore it, ask a question.

  9. #8
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    Default Re: Catch without a try error

    The one at the bottom.
    while (monthlypay1 < 0) {
                System.out.print("You need to enter positive numerical data!");
                break;
     
     
             }
                System.out.print("");
                System.out.print("Would you like to continue calculations( y / n)?");
     
                choice  = in.nextLine();
    So that little bit. I can't seem to find what's wrong with it. I've tried just retyping it cause sometimes I make errors via the name.
    I can't move it obviously because of how the loop works.

  10. #9
    Super Moderator Norm's Avatar
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    Default Re: Catch without a try error

    Why are there two variables with the same name? That is often a problem. Change the name of one of them so their names are different.
    If you don't understand my answer, don't ignore it, ask a question.

  11. The Following 2 Users Say Thank You to Norm For This Useful Post:

    Ancharius (October 30th, 2013), aussiemcgr (October 30th, 2013)

  12. #10
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    Default Re: Catch without a try error

    What Norm said is correct. A little thing called: "scope" hides variables. When code is executed, it looks for variable names in the closest scope. You have declared monthlypay1 as a class instance variable, but you have declared another variable with the same name in your main. Because of this, any reference to monthlypay1 in your main after the declaration will refer to the variable which only exists in your main, not your class instance variable. If you use Eclipse as your IDE, you can set it to warn you about variable hiding (other IDEs probably can as well, but I don't know how to set them up).

    Continuing on with that thought, variables declared inside of a method are not automatically given default values (whereas variables declared as class instance variables are). This includes primitives, like doubles. So the error you are getting is occurring because you did not initialize the monthlypay1 variable declared in your main method. But, the bigger problem, as Norm pointed out, is you variable hiding.
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  13. The Following 2 Users Say Thank You to aussiemcgr For This Useful Post:

    Ancharius (October 30th, 2013), Norm (October 30th, 2013)

  14. #11
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    Default Re: Catch without a try error

    Thanks guys I fixed it in class today. I had to set my double monthlypay1=0; and that made it work. As for the hiding my variable's I'll fix that up so my variables aren't hiding. But thanks for everything.
    topic solved. and program works.

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