Question

I’m bulding a program where the user can add ‘places’ to a map; the map is a background-image in a JPanel, and when clicked the program creates an instance of my city-class and draws/paints out a dot where the user clicked.

The drawing is made trough an over-riding of paintComponent; like this:

public void paintComponent(Graphics g) {
  super.paintComponent(g);
  setCursor(handCursor);
  g.setColor(Color.RED);
  g.fillOval(0, 0, 15, 15);
  g.setColor(Color.GRAY);
  g.fillOval(2, 2, 11, 11);
  g.setColor(Color.GRAY);
  g.drawString(globalString, 0, 25);
  g.setColor(Color.RED);
  g.drawString(globalString, 1, 26);
  bild.setCursor(oldCursor);
  bild.removeMouseListener(mln);
}

Now i’d like to make this method editable, in some way.

My goal is to have the ‘cities’ react to clicks (which already is settled in the city-class), one click makes the city ‘active’ and another makes it ‘inactive’.

My problem now is how to make changes in the drawing itself,
change:

  g.setColor(Color.GRAY);
  g.fillOval(2, 2, 11, 11);

to:

  g.setColor(Color.WHITE);
  g.fillOval(2, 2, 11, 11);

Is it possible to override the paintComponent once again, or can i make calls to the overridden version that i’ve created?

Edit:

I’m using two boolenas to settle if a city is selected or not, only two cities can be selected (and they are then avalible for further operations).

The boolens are sel1 and sel2

public void paintComponent(Graphics g) {

  if (sel1==false)
    { 
      super.paintComponent(g);
      setCursor(handCursor);
      g.setColor(Color.RED);
      g.fillOval(0, 0, 15, 15);
      g.setColor(Color.GRAY);
      g.fillOval(2, 2, 11, 11);
      g.setColor(Color.GRAY);
      g.drawString(globalString, 0, 25);
      g.setColor(Color.RED);
      g.drawString(globalString, 1, 26);
      bild.setCursor(oldCursor);
      bild.removeMouseListener(mln);
    }

else if(sel1==true)
    { 
      super.paintComponent(g);
      g.setColor(Color.BLACK);
      g.fillOval(0, 0, 25, 25);
      g.setColor(Color.WHITE);
      g.fillOval(2, 2, 5, 5);
      g.setColor(Color.WHITE);
      g.drawString(globalString, 0, 25);
      g.setColor(Color.BLACK);
      g.drawString(globalString, 1, 26);
    }

}

This code makes change, but only when a new city is created, and then it makes changes to all of them..

Sorry, i’m rather fresh to the logics here.

Answer 1

Try something like this:

public class City extends JComponent{
    private boolean active=false;
    protected int x;
    private int y;
    public City(int x, int y){
        setBounds(x, y, 20, 20);
        setPreferredSize(new Dimension(20,20));
        setMaximumSize(new Dimension(20,20));
        setMinimumSize(new Dimension(20,20));
    }
protected void paintComponent(Graphics g){
    super.paintComponent(g);
        if(active==true)
            active(g);

        else if(active==true)
            notActive(g);
    }


public void active(Graphics g){
    g.setColor(Color.RED);
    g.fillRect(0,0,getWidth(),getHeight());
}

public void notActive(Graphics g){
    g.setColor(Color.BLUE);
    g.fillRect(0, 0, getWidth(),getHeight());
}
public boolean clicked(boolean b){
active=b;
repaint();  //repaint whenever the flag active changes
}
public boolean isActive(){
   return active;
}

where x and y are coordinates

And in your main class:
//The listener which should be added to each city object

public class cityListener extends MouseAdapter{
    public void mouseClicked(MouseEvent e){
       City current=(City)e.getSource();

               if(current.active==false)
                  current.clicked(true);
              else if(current.active==true)
                  current.clicked(false);
    }
}