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Thread: Problem with first attempt at using my own classes

  1. #1
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    Default Problem with first attempt at using my own classes

    So in the code below I create an instance of my own triangle class and use one of its methods. The thing is I use one of my triangle classes methods in a method other the main method of my main program so I'm thinking it can't access it?

    anyway heres the code for my triangle class

     
    import java.util.Scanner;
     
    public class QudratullahMommandi_Triangle_06
    {
      Scanner keyboard = new Scanner(System.in);
       private double side1;
       private double side2;
       private double side3;
     
      public QudratullahMommandi_Triangle_06()
      { side1 = 0;
        side2 = 0;
        side3 = 0;
      }
     
      public QudratullahMommandi_Triangle_06(double sideOne, double sideTwo, double sideThree)
      { side1 = sideOne;
        side2 = sideTwo;
        side3 = sideThree;
      }
     
      public void giveLength(double firstSide, double secondSide, double thirdSide)
      { while (firstSide <= 0 ){
          System.out.println("The first side must be greater then zero " 
                              + "please enter a new value");
           firstSide = keyboard.nextDouble();
         }
        while (secondSide <=0){
          System.out.println("The second side must be greater then zero " 
                             + "please enter a new value");
           secondSide = keyboard.nextDouble();
           }
        while (thirdSide <=0){
          System.out.println("The third side must be greater then zero " 
                              + "please enter a new value");
           thirdSide = keyboard.nextDouble();
         }    
         side1 = firstSide;
         side2 = secondSide;
         side3 = thirdSide;
       }// end giveLength
     
       public void outPut()
       { System.out.println("The first side is " + side1 +"\n" +
                            "The second side is " + side2 + "\n" +
                            "The third side is " + side3);
       }// end outPut
     
       public double getPerim()
       { double perimeter = side1 + side2 + side3;
         return perimeter;
       }// end getPerim
     
       public double getArea()
       { double semiP = (side1+side2+side3)/2;
         double area = Math.sqrt(semiP*(semiP-side1)*(semiP-side2)*(semiP-side3));
         return area;
       }// end getArea


    Here's the code for my other class in which I use the triangle class
     
    import java.util.Scanner;
     
    public class QudratullahMommandi_S_06
    {  
     
       public static void main (String[]args)
        {
     
       QudratullahMommandi_Triangle_06 triangle1 = new QudratullahMommandi_Triangle_06();
     
       double perimeter;
       double area;
     
     
     
        Hello();
     
     
     
       triangle1.giveLength(4,5,6);
     
       perimeter = triangle1.getPerim();
     
       area = triangle1.getArea();
     
       Output();
     
     
     
     
     
        }// end main
     
     
     
     
       public static void Hello()
        { System.out.println("This program uses the triangle class and its methods\n" 
             + "to calculate the perimeter and area of a triangle given three side lengths");
              System.out.println("--------------------------------------");
              System.out.println("Qudratullah Mommandi");
        }
     
       public static String Output()
        { triangle1.outPut();
        }
     
    }// end class

    and here's the error message

    QudratullahMommandi_S_06.java:46: error: cannot find symbol
    { triangle1.outPut();
    ^
    symbol: variable triangle1
    location: class QudratullahMommandi_S_06
    1 error


  2. #2
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    Default Re: Problem with first attempt at using my own classes

    The variable traingle1 is declared and initialized inside the main() method so is local to main(). If you want to use triangle1 outside the main() method, then declare the variable as a class variable.

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