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Thread: If-Else Statement and Math

  1. #1
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    Default If-Else Statement and Math

    So, I am trying to make a program that does a math problem. Can someone please look at problem and see what i am doing wrong? The problem is "double Ea = EEa + KEa + GEa;" and it cant find EEa, KEa, or GEa. Here is the full code:
    import java.util.*;
    import java.util.Scanner;
    import java.*;
    /**
     * Write a description of class EnergyWork here.
     * 
     * @author (your name) 
     * @version (a version number or a date)
     */
    public class EnergyWork
    {
        // instance variables - replace the example below with your own
        private int x;
     
        /**
         * Constructor for objects of class EnergyWork
         */
        public EnergyWork()
        {
            // initialise instance variables
            x = 0;
        }
     
        public static void main(String[] args)
        {
            Scanner kb = new Scanner(System.in);
     
            System.out.println("Answer the next 3 questions about point A (Yes or No)");
     
            System.out.println("Is the object moving?");
     
            String Aa = kb.nextLine();
            if( Aa.equals("Yes")||( Aa.equals("yes")))
            {
                System.out.println("What is m?");
                double Aam = kb.nextInt();
                System.out.println("What is Va?");
                double Aav = kb.nextInt();
     
                double KEa = .5 * Aam * (Aav * Aav);
     
                System.out.print("Kinetic Energy = " + KEa);
            }
     
            System.out.println("Is the object elevated?");
     
            String Ab = kb.nextLine();
            if( Ab.equals("Yes") ||( Ab.equals("yes")))
            {
                System.out.println("What is m?");
                double Abm = kb.nextInt();
                System.out.println("What is Ha?");
                double Ha = kb.nextInt();
                double GEa = Abm * 9.8 * Ha;
     
                System.out.print("Gravitational Energy = " + GEa);
            }
     
            System.out.println("Is the object on a spring?");
     
            String Ac = kb.nextLine();
            if( Ac.equals("Yes")||( Ac.equals("yes")))
            {
                System.out.println("What is k?");
                double Ak = kb.nextInt();
                System.out.println("What is Xa?");
                double Xa = kb.nextInt();
                double EEa = .5 * Ak * (Xa * Xa);
     
                System.out.print("Elastic Energy = " + EEa);
            }
     
            double Ea = EEa + KEa + GEa;
            System.out.print("The energy of the system at point A =" + Ea);
        }
    }

    Thanks!


  2. #2
    Think of me.... Mr.777's Avatar
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    Default Re: If-Else Statement and Math

    You seriously need to know about scope and lifetime of variables.

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