Recieving "java.util.ClassCastException" when I'm trying to select a add city on a map

Question

I am creating a pathfinding-program where you should be able to add cities and then connect them with each other. The "adding city" part is working fine, but when I try to select the added city (or click anywhere else on the map) it gives up an error.

Here is the program code.

import java.util.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.File;

public class Pathfinder extends JFrame {

JButton hittaVäg, visaFörbindelse, nyPlats, nyFörbindelse, ändraFörbindelse;
JMenuBar menyBar;
JMenuItem ny, avsluta, hittaVägMeny, visaFörbindelseMeny, nyPlatsMeny, nyFörbindelseMeny, ändraFörbindelseMeny;
String str = System.getProperty("user.dir");
JFileChooser jfc;
BildPanel Bild = null;
MouseListener musLyss = new MouseListener();
MouseListener2 musLyss2 = new MouseListener2();
Stad från = null;
Stad till = null;
ListGraph listGraph = new ListGraph();

Pathfinder(){

    super("PathFinder");
    setLayout(new BorderLayout());
    setSize(590, 400);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setLocationRelativeTo(null);

    jfc = new JFileChooser(".");

    JPanel norra = new JPanel();
    add(norra, BorderLayout.NORTH);


    JButton hittaVäg = new JButton("Hitta väg");
    JButton visaFörbindelse = new JButton("Visa förbindelse");
    JButton nyPlats = new JButton("Ny plats");
    JButton nyFörbindelse = new JButton("Ny förbindelse");
    JButton ändraFörbindelse = new JButton("Ändra förbindelse");

    norra.add(hittaVäg);
    norra.add(visaFörbindelse);
    norra.add(nyPlats);
    norra.add(nyFörbindelse);
    norra.add(ändraFörbindelse);

    hittaVäg.addActionListener(new HittaLyss());
    visaFörbindelse.addActionListener(new VisaLyss());
    nyPlats.addActionListener(new NyPlatsLyss());
    nyFörbindelse.addActionListener(new NyFörbindelseLyss());
    ändraFörbindelse.addActionListener(new NyFörbindelseLyss());


    JMenuBar menyBar = new JMenuBar();
    setJMenuBar(menyBar);

    JMenu arkivMeny = new JMenu("Arkiv");
    JMenu operationerMeny = new JMenu("Operationer");

    menyBar.add(arkivMeny);
    menyBar.add(operationerMeny);


    JMenuItem ny = new JMenuItem("Ny");
    JMenuItem avsluta = new JMenuItem("Avsluta");

    arkivMeny.add(ny);
    arkivMeny.add(avsluta);

    ny.addActionListener(new NyLyss());
    avsluta.addActionListener(new AvslutaLyss());


    JMenuItem hittaVägMeny = new JMenuItem("Hitta väg");        
    JMenuItem visaFörbindelseMeny = new JMenuItem("Visa förbindelse");      
    JMenuItem nyPlatsMeny = new JMenuItem("Ny plats");
    JMenuItem nyFörbindelseMeny = new JMenuItem("Ny förbindelse");
    JMenuItem ändraFörbindelseMeny = new JMenuItem("Ändra förbindelse");

    operationerMeny.add(hittaVägMeny);
    operationerMeny.add(visaFörbindelseMeny);
    operationerMeny.add(nyPlatsMeny);
    operationerMeny.add(nyFörbindelseMeny);
    operationerMeny.add(ändraFörbindelseMeny);

    hittaVäg.addActionListener(new HittaLyss());
    visaFörbindelse.addActionListener(new VisaLyss());
    nyPlats.addActionListener(new NyPlatsLyss());
    nyFörbindelse.addActionListener(new NyFörbindelseLyss());
    ändraFörbindelse.addActionListener(new ÄndraFörbindelseLyss());

    pack();
    setVisible(true);


}
class MouseListener extends MouseAdapter{
    public void mouseClicked(MouseEvent mev){
        boolean o;
        o=true;
        for(;;){                
            String svar = JOptionPane.showInputDialog(null, "Platsens namn: ", "Ny Plats", JOptionPane.OK_CANCEL_OPTION);
            if (svar == null){
                o=false;
                break;  
            }else{
                if (svar.isEmpty()){
                JOptionPane.showMessageDialog(null, "Var vänlig ange ett giltigt namn!", "Error", JOptionPane.ERROR_MESSAGE);
                o=false;
            }


                if(o){
                int x = mev.getX();
                int y = mev.getY();
                Stad stad = new Stad (svar, x-10, y-10);
                listGraph.addNode(stad);
                Bild.add(stad);
                Bild.repaint();
                addMouseListener(musLyss2);
                validate();
                repaint();
                break;
            }
        }
    }
        Bild.removeMouseListener(musLyss);
        Bild.setCursor(Cursor.getDefaultCursor());
}
}
class MouseListener2 extends MouseAdapter{
    public void mouseClicked(MouseEvent mev){
        Stad s = (Stad)mev.getSource();

        if(s.getVald()==false){
            if (från==null){
                från = s;
                s.setVald(true);
        }
            else if(till==null){
                till = s;
                s.setVald(true);
            }
        }else{
            if (från==s){
                från = null;
                s.setVald(false);

            }else if (till==s){
                till = null;
                s.setVald(false);
        }

    }

}
}

class HittaLyss implements ActionListener{
    public void actionPerformed(ActionEvent ave){ 

    }

}
class VisaLyss implements ActionListener{
    public void actionPerformed(ActionEvent ave){ 

    }

}
class NyPlatsLyss implements ActionListener{
    public void actionPerformed(ActionEvent ave){ 

            Bild.addMouseListener(musLyss);
            Bild.setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));

    }

}
class NyFörbindelseLyss implements ActionListener{
    public void actionPerformed(ActionEvent ave){ 

    }

}
class ÄndraFörbindelseLyss implements ActionListener{
    public void actionPerformed(ActionEvent ave){ 

    }

}
class NyLyss implements ActionListener{
    public void actionPerformed(ActionEvent ave){ 
        int svar = jfc.showOpenDialog(Pathfinder.this);
        if (svar == JFileChooser.APPROVE_OPTION){
            File f = jfc.getSelectedFile();
            String filnamn = f.getAbsolutePath();
            if (Bild != null)
                remove(Bild);
            Bild = new BildPanel(filnamn);
            add(Bild, BorderLayout.CENTER);
            validate();
            repaint();
            pack();
        }
    }

}
class AvslutaLyss implements ActionListener{
    public void actionPerformed(ActionEvent ave){ 
        System.exit(0);
    }

}
public static void main (String[] args){
    new Pathfinder();
}
}

And this is the City class.

import javax.swing.*;
import java.awt.*;

public class Stad extends JComponent{
private String namn;
private boolean vald;
private int x, y;

public Stad(String namn, int x, int y){
    setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
    this.namn = namn;
    this.x=x;
    this.y=y;
    setBounds(x, y, 50, 50);


}

public void paintComponent(Graphics g){
    if (vald != true)
        g.setColor(Color.BLUE);
    else
        g.setColor(Color.RED);
    g.fillOval(0, 0, 15, 15);
    g.setColor(Color.BLACK);
    g.drawString(namn, 0, 30);
}

public int getX(){
    return x;
}

public int getY(){
    return y;
}

public void setVald(boolean vald){
    this.vald = vald;
    repaint();
}

public boolean getVald(){
    return vald;
}

public String getNamn(){
    return namn;
}


}

And this is the error I'm getting.

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: Pathfinder cannot be cast to Stad
at Pathfinder$MouseListener2.mouseClicked(Pathfinder.java:133)
at java.awt.Component.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Window.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

addMouseListener(musLyss2);

This line adds musLyss2 to the parent control which is Pathfinder. Then when the methode mouseClicked is called the source of MouseEvent will be Pathfinder. Then while you're trying to case it to Stad there will be a ClassCastException

You can use "stad.addMouseListener(musLyss2);" instead. Then the source of MouseEvent will be stad you can cast it to Stad