Java - Cannot be resolved to a variable?

Question

Hi Everyone,

I'm getting this weird error and eclipse is telling me my finalAmount variable can't be resolved. From looking at it I know it's outside of the scoop of the for statement and everytime I create a local variable and assign a value to it (it's zero) my program gets messed up.

My question is, how would I declare the finalAmount variable locally?

Thanks

import java.util.Scanner;

public class CompoundInterest {
    public static void main(String[] args){

        double rate;
        double amount;
        double year;

        System.out.println("This program, with user input, computes interest.\n" +
                "It allows for multiple computations.\n" +
                "User will input initial cost, interest rate and number of years.");

        Scanner input = new Scanner(System.in);

        System.out.println("What is the inital cost?");
        amount = input.nextDouble();

        System.out.println("What is the interest rate?");
        rate = input.nextDouble();
        rate = rate/100;

        System.out.println("How many years?");
        year = input.nextDouble();

        for(int x = 1; x < year; x++){
            double finalAmount = amount * Math.pow(1.0 + rate, year); 
// the below works but the problem is, it prints the statement out many times. I don't want that.
            /* System.out.println("For " + year + " years an initial " + amount + 
                    " cost compounded at a rate of " + rate + " will grow to " + finalAmount); */
        }


        System.out.println("For " + year + " years an initial " + amount + 
                " cost compounded at a rate of " + rate + " will grow to " + finalAmount);

    }



}

Answer 1 · 2014-01-03T04:10:54Z

January 3, 2014 4:10am

Shane,

Q: "eclipse is telling me my finalAmount variable can't be resolved" A: This is because you are declaring 'finalAmount' within the for loop. Once your for loop exits, 'finalAmount' goes out of scope. Meaning, Java has no clue it ever existed.

Q: "My question is, how would I declare the finalAmount variable locally?" A: From what I know, you cannot declare a variable within a loop of any kind if you want to retain the previous value. When you declare a variable within a loop this is what happens:

Your loop begins with an initial value of 0. (This is before the calculation takes place, double finalAmount;)
A value is calculated and assigned to finalAmount.
Your loop ends.
If you loop condition is still valid (x < year), repeat from step one (finalAmount is redeclared and initialized).

Someone please correct me if I said anything wrong about the above steps.

Here is my suggested change to your code, I hope this helps.

import java.util.Scanner;

public class CompoundInterest {
    public static void main(String[] args){

        double rate;
        double amount;
        double year;

        System.out.println("This program, with user input, computes interest.\n" +
                "It allows for multiple computations.\n" +
                "User will input initial cost, interest rate and number of years.");

        Scanner input = new Scanner(System.in);

        System.out.println("What is the inital cost?");
        amount = input.nextDouble();

        System.out.println("What is the interest rate?");
        rate = input.nextDouble();
        rate = rate/100;

        System.out.println("How many years?");
        year = input.nextDouble();

        /* Calculate the interest over a number of 'years' and 
           assign the value to 'finalAMount'
        */
        double finalAmount = 0;  // Perfectly legal to do this since finalAmount isn't used prior to this.
        for(int x = 1; x < year; x++){
            finalAmount = amount * Math.pow(1.0 + rate, year); 
        }


        System.out.println("For " + year + " years an initial " + amount + 
                " cost compounded at a rate of " + rate + " will grow to " + finalAmount);

    }
}

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Shane McC

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Java - Cannot be resolved to a variable?

1 Answer

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Shane McC

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Shane McC

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