Class is not abstract and does not override abstract method

Question

So I ve been working on a homework on abstraction for my programming class and fell into a problem  The goal for me right now is to be able to use abstraction  then later be able to draw with rectangles and ovals a simple city  like a rectangular building or a oval light on a light post    The error I am receiving when I compile is  MyTestApp Rectangle is not abstract and does not override abstract method drawEllipse java awt Graphics  in MyTestApp Shape  This Error shows up on the line  class Rectangle extends Shape   right below the class Shape   My question is what am I doing wrong with my abstraction  I ve been messing with the constructors and draw   methods in classes Rectangle and Ellipse for a while now and still to no luck happen to find a solution   Code is below   import java awt    import javax swing     public class MyTestApp extends JPanel       Rectangle rect      Ellipse oval      public static void main String    args            MyTestApp myTestApp   new MyTestApp             myTestApp test               public MyTestApp        creates the jframe         JFrame frame   new JFrame  MyClass Driver            setBackground new Color 200  250  200            setPreferredSize new Dimension 500  400            frame add this           frame pack            frame setVisible true              public void delay int msecs            try               Thread sleep msecs             catch  InterruptedException e                         public void paint Graphics g     paints the rectangle and ellipse         super paint g           if  rect    null              rect drawRectangle g           if  oval    null              oval drawEllipse g              public void test      gives the x y position  width height  and fill outline color for the rectangle and oval         delay 1000           rect   new Rectangle 20  30  23  75  Color GREEN  Color BLUE           oval   new Ellipse 10  10  10   34  Color RED  Color MAGENTA           repaint               public abstract class Shape   abstract class Shape that sets the x y  width height  and colors for the shapes         private int x  y  width  height          private Color fillColor          private Color outlineColor          public Shape int x  int y  int width  int height  Color fillColor  Color outlineColor                setXY x  y               setSize width  height               setFillColor fillColor               setOutlineColor outlineColor                        public boolean setXY int x  int y                this x   x              this y   y              return true                     public void setSize int width  int height                if  width  gt  0                  this width   width              if  height  gt  0                  this height   height                     public boolean setFillColor Color fillColor               if  fillColor    null  return false              this fillColor   fillColor               return true                     public boolean setOutlineColor Color outlineColor               if  outlineColor    null  return false              this outlineColor   outlineColor               return true                     public Color getFillColor                 return fillColor                      public Color getOutlineColor                 return outlineColor                      public abstract void drawRectangle Graphics g    do i need two          public abstract void drawEllipse Graphics g    do i need both            class Rectangle extends Shape              where the error shows         public Rectangle int x  int y  int width  int height  Color fillColor  Color outlineColor                super x  y  width  height  fillColor  outlineColor                      public void drawRectangle Graphics g    draws the retangle             g setColor fillColor               g fillRect x  y  width  height               g setColor outlineColor               g drawRect x  y  width  height                       class Ellipse extends Shape          public Ellipse int x  int y  int width  int height  Color fillColor  Color outlineColor                super x  y  width  height  fillColor  outlineColor                      public void drawEllipse Graphics g    draws the ellipse             g setColor fillColor               g fillOval x  y  width  height               g setColor outlineColor                   g drawOval x  y  width  height                               Thanks for reading and helping

User · Answer

If you re trying to take advantage of polymorphic behavior  you need to ensure that the methods visible to outside classes  that need polymorphism  have the same signature  That means they need to have the same name  number and order of parameters  as well as the parameter types   In your case  you might do better to have a generic draw   method  and rely on the subclasses  Rectangle  Ellipse  to implement the draw   method as what you had been thinking of as  drawEllipse  and  drawRectangle

User · Answer

Both classes Rectangle and Ellipse need to override both of the abstract methods   To work around this  you have 3 options    Add the two methods Make each class that extends Shape abstract Have a single method that does the function of the classes that will extend Shape  and override that method in Rectangle and Ellipse  for example   abstract class Shape                  void draw Graphics g        And      class Rectangle extends Shape           void draw Graphics g                                         Finally      class Ellipse extends Shape           void draw Graphics g                                         And you can switch in between them  like so       Shape shape   new Ellipse        shape draw                  shape   new Rectangle        shape draw               Again  just an example

[java] Class is not abstract and does not override abstract method

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