A question on JInternalFrame of Swing. Let see the code

Question

Hello everybody,
I am setting up a Frame that contains 2 JInternalFrames in its desktopPane. The first JInternalFrame is to show the map. The second one have some check box. What I wanna do is, when I check the CheckBox in the second JInternalFrame, after getting the result from Database, it show the result on Map. The result will be some red ellipses on the first JInternalFrame.
The code work well with Database. But I really need your help to do with the event on InternalFrame
Thanks in advance !
Quin,
Here is the code of the main Frame:
import java.awt.*;
import java.awt.event.*;
import java.awt.font.*;
import javax.swing.*;
import javax.swing.event.*;
import java.util.*;
import java.io.*;
import java.net.*;
import java.beans.*;
public class MapLocator
     public static void main(String [] args)
          JFrame frame = new DesktopFrame();
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setVisible(true);
Create a desktop frames that contains internal frame
class DesktopFrame extends JFrame implements ActionListener
     public DesktopFrame()
          super("Map Locator v.1.0.0");
          this.setSize(new Dimension(WIDTH,HEIGHT));
          desktop = new JDesktopPane();
          this.setContentPane(desktop);
          this.createInternalFrame(
               new mapPanel(),"Ban do Thanh pho Ho Chi Minh",0,0,480,515);
          this.createInternalFrame(
               new commandPanel(),"Chu thich va tim kiem",480,0,320,515);
Create an internal frame on the desktop.
@param c the component to display in the internal frame
@param t the title ofthe internal frame.
     public void createInternalFrame(JPanel c, String t,int ifx, int ify, int ifwidth, int ifheight)
             final JInternalFrame iframe = new JInternalFrame(t,
             true//resizeable
             ,true//closable
             ,true//maximizable
             ,true//iconifiable
             iframe.getContentPane().add(c);
             desktop.add(iframe);
             iframe.setFrameIcon(new ImageIcon("new.gif"));
             //add listener to confirm frame closing
             iframe.addVetoableChangeListener(new VetoableChangeListener()
                  public void vetoableChange(PropertyChangeEvent event)
                       throws PropertyVetoException
                       String name = event.getPropertyName();
                       Object value = event.getNewValue();
                       //we only want to check attempts to close a frame
                       if(name.equals("closed") && value.equals(Boolean.TRUE))
                            //ask user if it is ok to close
                            int result =
                  JOptionPane.showInternalConfirmDialog(iframe,"OK to close");
                            //if the user doesn't agree, veto the close
                            if(result != JOptionPane.YES_OPTION)
                  throw new PropertyVetoException("User cancel the close",event);
             iframe.setVisible(true);
             iframe.setLocation(ifx,ify);
             iframe.setSize(new Dimension (ifwidth, ifheight));
     private static final int WIDTH = 800;
     private static final int HEIGHT = 600;
     private JDesktopPane desktop;
     private int nextFrameX;
       private int nextFrameY;
        private int frameDistance;
     private JMenuBar menuBar;
     private JMenu fileMenu, viewMenu, searchMenu, windowMenu, helpMenu;
     private JRadioButtonMenuItem javalaf, liquidlaf, motiflaf, windowlaf, threedlaf;
}Below is the code of first JInternalFrame
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.sql.*;
import java.awt.font.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.Random;
import java.util.*;
import com.sun.image.codec.jpeg.*;
Create a canvas that show a map
public class mapPanel extends JPanel
     implements MouseMotionListener, MouseListener
     public mapPanel()
          addMouseMotionListener(this);
          addMouseListener(this);
Unbarrier the comment below to see how the map model work
//Unbarrier this to see -->
         try
            InputStream in = getClass().getResourceAsStream(nameOfMap);
            JPEGImageDecoder decoder = JPEGCodec.createJPEGDecoder(in);
            mImage = decoder.decodeAsBufferedImage();
            in.close();//Close dong nhap
          catch(ImageFormatException ie)
          { System.out.println ("Error on formating image");}
          catch(IOException ioe)
          { System.out.println ("Error on input/ouput image");}
          catch(Exception e){}
Connect to database
          connDB();
          String addQuery = "";
          try
          Get the relation amongs points
               int idStart = 0;
               int idEnd = 0;
               addQuery ="SELECT IDStart, IDEnd FROM 2Diem";
               rs = stmt.executeQuery(addQuery);
               int incre = 0;
               while(rs.next())
                    idStart = rs.getInt(1);
                    Rel.add(incre, new Integer(idStart));
                    incre ++;
                    idEnd = rs.getInt(2);
                    Rel.add(incre, new Integer(idEnd));
                    incre ++;
     Load the Coordination of the points to hash table
               int idPoint = 0;
               int XP = 0;
               int YP = 0;
               addQuery ="SELECT IDDiem, CoorX, CoorY FROM Diem";
               rs = stmt.executeQuery(addQuery);     
               while(rs.next())
                    idPoint = rs.getInt(1);
                    XP = rs.getInt(2);
                    YP = rs.getInt(3);
                    hashX.put(new Integer(idPoint), new Integer(XP));
                    hashY.put(new Integer(idPoint), new Integer(YP));
     Create Points to draw the Line
               line = new Line2D[(Rel.size())/2];
               for(int i = 0, k = 0; i < Rel.size();i++, k = k+2)
                    X1 = Integer.parseInt(""+hashX.get(Rel.elementAt(i)));
                    Y1 = Integer.parseInt(""+hashY.get(Rel.elementAt(i)));
                    i++;
                    X2 = Integer.parseInt(""+hashX.get(Rel.elementAt(i)));
                    Y2 = Integer.parseInt(""+hashY.get(Rel.elementAt(i)));
                    line[k/2] = new Line2D.Double(X1,Y1,X2,Y2);
          catch(SQLException sqle){}
     private Hashtable hashX = new Hashtable();
     private Hashtable hashY = new Hashtable();
     private Vector Rel = new Vector(100,10);
     private Vector vecBackX = new Vector(10,2);
     private Vector vecBackY = new Vector(10,2);
     private int X1 = 0, X2 = 0, Y1 = 0, Y2 = 0;
     Draw the image to show
     public void paintComponent(Graphics g)
          super.paintComponent(g);
          Graphics2D g2 = (Graphics2D) g;
          g2.setRenderingHint(
               RenderingHints.KEY_ANTIALIASING,
               RenderingHints.VALUE_ANTIALIAS_ON);
    //     g2.drawImage(mImage,0,0,null);
    Paint the background with light Gray
          g2.setPaint(Color.lightGray);
          g2.fill(new Rectangle2D.Double(0,0,480,480));          
         fillBack(g2);
    Draw the street with its border is white, its background is orange
         g2.setPaint(Color.white);
          g2.setStroke(new BasicStroke(14,BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
          for(int k = 0; k < Rel.size()/2; k++)
               g2.draw(line[k]);
          g2.setPaint(Color.orange);
          g2.setStroke(new BasicStroke(10,BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
          for(int k = 0; k < Rel.size()/2; k++)
               g2.draw(line[k]);
     Draw the grid on map
          g2.setPaint(Color.white);
          g2.setStroke(new BasicStroke(1));
          drawGrid(g2);
          if(point != null)
               g2.setPaint(Color.red);
               g2.fillOval(point.x - 3, point.y - 3, 7, 7);
Draw the Background with tree and water
@param g2 the Graphics2D that used to draw shapes
     private void fillBack(Graphics2D g2)
          Draw the background for map
          try
               int BackX = 0;
               int BackY = 0;
               int incre = 0;
               backGround = new GeneralPath[3];
               for(int idBack = 1; idBack <= 3; idBack++)
Since we use the vector for each background(tree / water), we have to
refresh the vector before it can add new path inside
                    vecBackX.clear();
                    vecBackY.clear();
                    String addQuery = "SELECT CoorX, CoorY FROM BackCoor WHERE "
                    + " IDBack =" + idBack;
                    rs = stmt.executeQuery(addQuery);
                    while(rs.next())
                         BackX = rs.getInt(1);
                         BackY = rs.getInt(2);
This will take the point into vector
                         vecBackX.add(incre,new Integer(BackX));
                         vecBackY.add(incre,new Integer(BackY));
                         incre++;
Design the shapes of path
                         backGround[(idBack - 1)] =
                              new GeneralPath(GeneralPath.WIND_EVEN_ODD);
                         backGround[(idBack - 1)].moveTo(
                              Integer.parseInt(""+vecBackX.elementAt(0)),
                              Integer.parseInt(""+vecBackY.elementAt(0)));
                         for(int i = 1; i < vecBackX.size(); i++)
                              backGround[(idBack - 1)].lineTo(
                                   Integer.parseInt(""+vecBackX.elementAt(i)),
                                   Integer.parseInt(""+vecBackY.elementAt(i)));
                         backGround[(idBack - 1)].lineTo(
                                   Integer.parseInt(""+vecBackX.elementAt(0)),
                                   Integer.parseInt(""+vecBackY.elementAt(0)));
                         backGround[(idBack - 1)].closePath();
Here we have 3 Path that represented to tree and water
The first and second one is tree.
The last one is water.
Draw the path now
                         if(idBack == 3)
                              g2.setPaint(Color.cyan);
                              g2.fill(backGround[(idBack - 1)]);
                         else
                              g2.setPaint(Color.green);
                              g2.fill(backGround[(idBack - 1)]);
                         incre = 0;
          catch(SQLException sqle)
               System.out.println ("Khong ve duoc back ground");
Create the grid on map
@param g2 the Graphics2D that used to draw shapes
     private void drawGrid(Graphics2D g2)
          try
             String Query =
             "SELECT * FROM Grid";
             rs = stmt.executeQuery(Query);
             GridX = new Vector(100,2);
             GridY = new Vector(100,2);
             GridW = new Vector(100,2);
             GridH = new Vector(100,2);
             int incr = 0;
             while(rs.next())
                  gridX = rs.getInt(2);
                  gridY = rs.getInt(3);
                  gridW = rs.getInt(4);
                  gridH = rs.getInt(5);
                  GridX.add(incr, new Integer(gridX));
                  GridY.add(incr, new Integer(gridY));
                  GridW.add(incr, new Integer(gridW));
                  GridH.add(incr, new Integer(gridH));
                  incr ++;
             rec = new Rectangle2D.Double[GridX.size()];
             for(int i = 0; i < GridX.size(); i++)
                  gridX = Integer.parseInt(""+GridX.elementAt(i));
                  gridY = Integer.parseInt(""+GridY.elementAt(i));
                  gridW = Integer.parseInt(""+GridW.elementAt(i));
                  gridH = Integer.parseInt(""+GridH.elementAt(i));
                  rec[i] = new Rectangle2D.Double(gridX, gridY, gridW, gridH);
                  g2.draw(rec);
catch(SQLException sqle){}
private Vector GridX, GridY, GridW, GridH;
private int gridX = 0, gridY = 0, gridW = 0, gridH = 0;
Fill the point
     public void placePoint(Graphics2D g2,Point p)
          g2.setPaint(Color.red);
          g2.fill(new Ellipse2D.Double(p.x - 3, p.y - 3, 7,7));
Create connection to Database
     public void connDB()
          System.out.println ("Connecting to Database");
          String fileName = "Pro.mdb";
          String data = "jdbc:odbc:Driver={Microsoft Access Driver " +
     "(*.mdb)};DBQ=" + fileName + ";DriverID=22";
          try
               Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
               conn = DriverManager.getConnection(data,"","");
               stmt = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,
                    ResultSet.CONCUR_UPDATABLE);
          catch(ClassNotFoundException ce)
          { System.out.println ("Khong tim thay Driver"); }
          catch(SQLException sqle)
          { System.out.println ("Loi SQL trong khi Connect"); }
          Statement stmt = null;
          ResultSet rs = null;
          Connection conn = null;     
This one is the model map to draw
     private String nameOfMap = "map.jpg";
     private BufferedImage mImage;
Initialize the path and shapes to draw
     private Line2D line[];
     private Rectangle2D.Double rec[];
     private GeneralPath backGround[];
     private Point point;
     private int changeColor = 0;
The last one is:
import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
import java.awt.event.*;
import java.sql.*;
public class commandPanel extends JPanel implements ActionListener
Initial check box
     JCheckBox uyBanNhanDan = new JCheckBox();
     JCheckBox nganHang = new JCheckBox();
     JCheckBox buuDien = new JCheckBox();     
     JCheckBox khachSan = new JCheckBox();     
     JCheckBox benhVien = new JCheckBox();          
     JCheckBox cho = new JCheckBox();     
     JCheckBox nhaHat = new JCheckBox();     
     JCheckBox daiHoc = new JCheckBox();     
     JCheckBox thuvien = new JCheckBox();     
     JCheckBox nhaTho = new JCheckBox();     
     public commandPanel()
          this.setLayout(new BorderLayout());
          this.setBorder(BorderFactory.createCompoundBorder(
                      BorderFactory.createTitledBorder("***Chu dan***"),
                      BorderFactory.createEmptyBorder(5,5,5,5)));
Create the combobox to show information
          uyBanNhanDan.setText("Uy Ban ND Quan");
          nganHang.setText("Ngan Hang");
          buuDien.setText("Buu Dien");
          khachSan.setText("Khach San");
          benhVien.setText("Benh Vien");
          cho.setText("Cho - Mua Sam");
          nhaHat.setText("Nha Hat");
          daiHoc.setText("Dai Hoc - Dao Tao");
          thuvien.setText("Thu Vien - Nha Sach");
          nhaTho.setText("Nha Tho - Chua");
          uyBanNhanDan.addActionListener(this);
          nganHang.addActionListener(this);
          buuDien.addActionListener(this);
          khachSan.addActionListener(this);
          benhVien.addActionListener(this);
          cho.addActionListener(this);
          nhaHat.addActionListener(this);
          daiHoc.addActionListener(this);
          thuvien.addActionListener(this);
          nhaTho.addActionListener(this);
          uyBanNhanDan.setActionCommand("1");
          nganHang.setActionCommand("2");
          buuDien.setActionCommand("3");
          khachSan.setActionCommand("4");
          benhVien.setActionCommand("5");
          cho.setActionCommand("6");
          nhaHat.setActionCommand("7");
          daiHoc.setActionCommand("8");
          thuvien.setActionCommand("10");
          nhaTho.setActionCommand("11");
          JPanel secP = new JPanel();
          secP.setLayout(new GridLayout(5,2));
          secP.add(uyBanNhanDan);
          secP.add(nganHang);
          secP.add(buuDien);
          secP.add(khachSan);
          secP.add(benhVien);
          secP.add(cho);
          secP.add(nhaHat);
          secP.add(daiHoc);
          secP.add(thuvien);
          secP.add(nhaTho);
          this.add(secP,BorderLayout.NORTH);
     public void actionPerformed(ActionEvent event)
          int x = 0;
          int y = 0;
          try
               mapPanel mp = new mapPanel();
               int idDiaDanh = 0;
               if(event.getActionCommand() == "1")
                    idDiaDanh = 1;
               String Query =
               "SELECT CoorX, CoorY FROM MoTa WHERE IDDiaDanh =" + idDiaDanh;
               mp.rs = mp.stmt.executeQuery(Query);
               while(mp.rs.next())
/*I have problem here*/
/*Process the event for me*/          x = mp.rs.getInt(1);
                    y = mp.rs.getInt(2);
                    Graphics g2 = mp.getGraphics();
                    mp.paintComponents(g2);
                         g2.setPaint(Color.red);
                         g2.fill(new Ellipse2D.Double(x - 3, y - 3, 7, 7));     
          catch(SQLException sqle){}

Answer 1

Strings are Objects.
String[] strings = new String[3];
String[0]="abcde";Right here, you are initializing the String array, and the String at index 0.
JButton[] buttons = new JButton[2];
buttons[0].setText("abcde");Right here, you are initializing the JButton array, but not any of the JButtons in the array. You then try to use the setText() method on a null JButton.