Thread: Help with checking to see which menuItem has been selected

Hey, I've uploaded my program, so that you can test it, seeing as pasting large chunks of code wont let you see what my problem is.

Link: http://www.filedropper.com/calculations_1

In MyControlPanel class I have this line:

DrawShape drawShape = new DrawShape(20,20,shapeSize,theShape);

Which is used to send the coords 'x' and 'y', 'shapeSize' and 'theShape' to the DrawShape class

I then have a paintComponent which is used to draw one of the three shapes depending on which is chosen from the menu, for example if the Square is chosen, a square will be drawn, using the coords x and y(default 20,20) and also the shapeSize(taken from the sliders value)

but, before it draws a shape it needs to recognize which shape has been chosen, seeing as I have passed in myShape, and assigned it to theShape, I should be able to, some how, compare 'theShape' to 'Circle' and if it matches it will drawn a circle, etc.

I tried using:

if(theShape == Square)

but then found that i cant just simply do that.

Can anyone help me ? how do i check to see which shape it is that has been chosen.

It would be much easier if you downloaded my program, if possible.

I will post all the code if needed.

Did you consider using instanceof?

But I think I've given you this advice before: Each shape should know how to draw itself, so simply specifying thisShape.draw() with the necessary parameters, including the Graphics instance the shape will be drawn on, should do what needs to be done.

So in inside each of my shape classes(circle, square and triangle), i should add a paint component ?

for example,

public void paintComponent(Graphics g)
            {
                Graphics2D g2 = (Graphics2D) g;
 
                g2.fillRect( x , y , length, length);
                g2.setColor(Color.BLACK);
            }

Edit:
instanceof didnt work, no shape appeared when i selected one

No. You pass the Graphics object to the shape's draw method from inside the paintComponent() method of the component on which the drawing is being done, and the shape draws itself on that object.

I don't have time to write an example for you but will later if you'd like.

could you please write an example later for me, I'm completely lost! I'm making this program messier and messier! I've got bits of everything everywhere. Are you able to download my program? If so could you have a look at it and give me a clue to what needs fixed, if not an example of the painting will be great!

thanks.

Will do. Sometime today, but I can't promise when. When you make a statement like:

instanceof didnt work, no shape appeared when i selected one.

include code, even a line or two, to show what you tried. You may have done it completely wrong, in the wrong place, or . . . We can't help much with "I changed it and it didn't work."

Well I'm kind of desperate to get this finished today!

Sorry, I'm just giving up all hope, I should be able to figure this out, but I can't.

well i tried this:

package calculations;
 
import java.awt.*;
 
import javax.swing.JPanel;
 
class DrawShape extends JPanel
{
     private int x = 50, y = 10; 
     int length = 50;
 
     private MyShape theShape;//selected shape
 
     public DrawShape(int newX, int newY, int newLength, MyShape myShape)
     {
         x = newX;
         y = newY;
         length = newLength;
         theShape = myShape;
 
         setPreferredSize(new Dimension(800, 650));
 
         setBackground(Color.WHITE);
 
         repaint() ;
     }
 
     //used to get the selected shape from
     public void setShape(MyShape suppliedShape)
     {       
         theShape = suppliedShape;
     }
 
     @Override
            public void paintComponent(Graphics g)
            {
                Graphics2D g2 = (Graphics2D) g;
 
                super.paintComponent(g2);
 
                BasicStroke pen = new BasicStroke(4F);
                g2.setStroke(pen);
 
                if(theShape instanceof Square);
                {
                //Square
                    g2.fillRect( x , y , length, length);
                    g2.setColor(Color.BLACK);
                }
                if(theShape instanceof Circle)
                {
                //Circle
                    g2.fillOval(x+100 , y , length, length);
                    g2.setColor(Color.BLUE);
                }
                if(theShape instanceof Triangle)
                {
                //Triangle
                    int xCoords[] = {x+200,x+200,x+260};
                    int yCoords[] = {y,y+50,y+50};
 
                    g2.fillPolygon(xCoords, yCoords, 3);
                    g2.setColor(Color.RED);
                }
            }
 }

The code does not draw any shapes, just produces a white box in my program(where the shape is meant to be drawn):
wefwef.jpg

That code is meant to, when i select a shape from the menu, say i picked Square, it would draw a square, with width/height = to the sliders value. Meaning when i increase the slider value, the shape grows in size.

That semicolon was there by accident, even though it was there though, it didn't do what was in the {}.

EDIT: Oh yeah, I removed the semicolon and tried it, still nothing.

Did the results change when the semicolon was removed?

no nothing changed, still no shape being drawn

I add the DrawShape within MyControlPanel constructor, is it called a constructor?

    public MyControlPanel() 
    {
        initComponents();
 
        //JSlider setup
        jSlider = new JSlider(JSlider.HORIZONTAL, min, max, initial);
        jSlider.setMajorTickSpacing(10);
        jSlider.setMinorTickSpacing(1);
        jSlider.setPaintLabels(true);
        jSlider.setPaintTicks(true);
        jSlider.setValue(50);
 
        jSlider.addChangeListener(new MyChangeAction());
 
        //create instance of jTexts          
        jText1 = new JTextField();
        jText2 = new JTextField();
 
        //setText for jTexts
        jText1.setText("          ");
        jText2.setText("          ");
 
        //create instance of labels
        jLabel1 = new JLabel();
        jLabel2 = new JLabel();
        jLabel3 = new JLabel();
        jLabel4 = new JLabel();
 
        //setText for jLabels
        jLabel1.setText("Shape Dimension = ");
        jLabel2.setText("     Boundary Length = ");
        jLabel3.setText("     Area = ");
        jLabel4.setText("");
 
        jPanelPaint= new JPanel();
        jPanelSlider = new JPanel();
 
        DrawShape drawShape = new DrawShape(20,20, shapeSize, theShape);
 
        //adding components
        this.add(drawShape);
        this.add(jSlider);
        this.add(jLabel1);
        this.add(jLabel4);
        this.add(jLabel2);
        this.add(jText1);
        this.add(jLabel3);
        this.add(jText2);
 
        setLayout(new FlowLayout());
    }

I call the setShape() method within each of the three actionListeners for the menuItems within the MyFrame class, allowing me to tell which shape has been selected.

I have this method within the MyControlPanel class:

public void setShape(MyShape suppliedShape)
    {       
        theShape = suppliedShape;
    }

The actionListeners look like this, within the MyFrame class:

public class MySquareAction implements ActionListener
    {
    @Override
        public void actionPerformed(ActionEvent e)
        {
            myShape = new Square();//sets myShape as an instance of Square
            controlPanel.setShape(myShape);//sends myShape to MyControlPanel
        }  
    }

I get the size from the slider changeListener, which is in the MyControlPanel class:
Slider changeListener

public class MyChangeAction implements ChangeListener
        {
            @Override
            public void stateChanged(ChangeEvent e) 
            {                
                int sliderValue = jSlider.getValue();
                shapeSize = sliderValue;
                double area;
                double boundaryLength;
 
                String str = Double.toString(sliderValue);
                jLabel4.setText(str);
 
                area = theShape.getArea(sliderValue);
                boundaryLength = theShape.getBoundaryLength(sliderValue);
 
                jText1.setText(Double.toString(Math.round(boundaryLength)));
                jText2.setText(Double.toString(Math.round(area))); 
                repaint();
            }            
        }

before i tried passing in the shape and value, i hardcoded the size, and used only the code to draw a square, this worked, i could increase the hardcoded value, run the program, and the shape would be drawn bigger. Then i attempted to pass in the values with what i have now, and it isn't working.

this is what happens when i force the shape to be a square, then select square and move the slider:
sderh.jpg

how do i get them to be the same variable ?

EDIT: yeah, when i use a 'System.out.println("shape = "+myShape);' in the DrawShape constructor it comes back as null, do you know how i can fix this ?

I understand what you mean, but how do I fix my problem ? I cant figure it out

do you mean the setShape() method which i used?

I don't understand how i would do it with the DrawShape class, because it requires three int values when creating an instance of it:

public DrawShape(int newX, int newY, int newLength)

so i would have to do this within the MyFrame class:

DrawShape drawShape = new DrawShape(int,int,int);

though what values would i use for the int's ?

how can i call setShape() function on drawShape? seeing as i cant create an instance of DrawShape because it requires 3 int values ??

DrawShape drawShape = new DrawShape(int,int,int);

ertherth.jpg

right, so in the DrawShape class if I run:

public DrawShape(int newX, int newY, int newLength, MyShape shape)
     {
         x = newX;
         y = newY;
         length = newLength;
         theShape = shape;
         System.out.println("shape = "+theShape);
 
         setPreferredSize(new Dimension(800, 650));
 
         setBackground(Color.WHITE);
 
         repaint() ;
     }

the sout, returns the correct shape when i click on a shape and then move the slider, plus it draws the correct shape, my only problem is that it does this:
multiple paints.jpg
It paints god knows how many white boxes, with the shape drawn in, and the slider/textboxes and labels disappear, this is probably to do with my layout, can you tell me what would do this ? or what the best way to lay out this would be?

I found what the problem is, it is because i am calling add(drawShape); within my jSlider stateChanged.

But it needs to be called within the stateChanged or else it will not work, is there a way to remove a object from the screen? i tried remove(drawShape); at the start so that it would remove it, then add it at the bottom again, but that didnt work.

any help with this ?