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Thread: How can I access my secondary interface method in my for loop?

  1. #1
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    Default How can I access my secondary interface method in my for loop?

    I can't access my el.print() in my for loop. These are four different files. I have two interfaces with separate names. I can't combine them or add or remove and new methods. I can change current methods however. There are similar classes as to triangle for square, rectangle, etc. Circle cannot access Printable.print, the other three can.

    public class InterfaceApp 
    {
        public static void main( String[] args )
        {
            Rectangle myRectangle = new Rectangle( 6, 3 );
            Square mySquare = new Square( 5, 5 );
            Triangle myTriangle = new Triangle( 6 );
            Circle myCircle = new Circle( 5 );
     
            System.out.println( myRectangle );
            System.out.println();
            System.out.println( mySquare );
            System.out.println();
            System.out.println( myTriangle );
            System.out.println();
            System.out.printf( myCircle + "%nDiameter: %d%nCircumference: %.1f%n%n",
                    myCircle.diameter(), myCircle.circumference() );
     
            System.out.printf( "Shape Array: %n-----------%n" );
     
            Shape[] myShapes = { mySquare, myRectangle, myTriangle, myCircle };
     
            mySquare.print();
            myRectangle.print();
            myTriangle.print();
     
            for ( Shape el : myShapes )
            {
     
                System.out.printf( el + "%nPerimeter: %.1f%nArea: %.1f%n", 
                        el.perimeter(), el.area() );
     
                if (!( el instanceof Circle ))
                {
                    el.print();
                }
     
            }
        }
    }
     
    public class Triangle implements Shape, Printable
    {
        private final int leg;
        private final double hypotenuse;
     
        public Triangle( int l )
        {
            leg = l;
            hypotenuse = leg*Math.sqrt( 2.0 );
        }    
     
        public int getLeg()
        {
            return leg;
        }
     
        public double getHypotenuse()
        {
            return hypotenuse;
        }
     
        @Override
        public String toString()
        {
            return String.format( "Triangle(%d)", leg );
        }
     
        @Override
        public double perimeter() 
        {
            return 2*leg + hypotenuse;
        }
     
        @Override
        public double area() 
        {
            return .5*(Math.pow( leg,  2 ));    
        }
     
        @Override
        public void print() 
        {
            String gap = "";
            System.out.println( "* " );
            for ( int i = 1; i < leg; i++ )
            {
     
                if ( i == leg - 1 )
                {
                    for ( int j = 0; j < leg; j++ )
                    {
                        if ( j == leg - 1 )
                        {
                            System.out.println( "* ");
                        }
                        else
                        {
                        System.out.printf( "* " );
                        }
                    }
                }
                else
                {
                    if ( i == 1 )
                    {
                        gap = "";
                    }
                    else 
                    {
                        gap += "  ";
                    }
                System.out.println( "* " + gap + "* " );
                }
            }
        }
    }
     
    public interface Shape 
    {
        double perimeter();
        double area();
    }
     
    public interface Printable 
    {
        void print();
    }


  2. #2
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    Default Re: How can I access my secondary interface method in my for loop?

    It could be because im tired but i dont see where el is declared.

  3. #3
    Super Moderator Norm's Avatar
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    Default Re: How can I access my secondary interface method in my for loop?

    I can't access
    If there are error messages, copy the full text of the messages and paste it here.


    The Shape interface does not have a print() method.
    The Printable interface does have a print() method. Make el a Printable.
    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:

    bdennin (February 12th, 2013)

  5. #4
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    Default Re: How can I access my secondary interface method in my for loop?

    I just extended Shapes with Printable. Problem solved.

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