Mohamad Samy

Thanks for you all my friends

Today 24/04/2014
I passed the exam of OCAJP 7
I would like to thank this great community where i found real help also to thank K&B SCJP 6 which was a great book to prepare my self.
I am mohamad samy
Chemical engineer but a java lover
Egypt

Ok i got yoy. You mean some other codes in Jdk called those overriden metods

say i have jtable with anonymous class like
JTable table = new JTable(new MyTableMode()){ public String getToolTipText(MouseEvent e) {//any thing to do} protected JTableHeader createDefaultTableHeader(){} };
those methods are in the JTable API and i implement them in the anonymous class to match my need. which part code of program will call them to do their funciton to show the tool tip for example or the JVM will call them as in the rest of the program there is nothing calling them at all. please, explain it.

I have the following code to check the winner of the TicTacToe game, when any condition within is satisfied (for example here is first condition at line 8 ) I could send the current player a message with his result either he won or lost but I can't give the result of the game to the other player as I am in the current player thread, how could I do this.
I tried to switch to the other player through
currentPlayer = (currentPlayer+1)%2 but that don't work either
public boolean isGameOver() { if(board[0].equals("X") || board[0].equals("O"))//to assure any player had really played { //check on the row equality if(board[0].equals(board[1]) && board[1].equals(board[2])) { players[currentPlayer].output.format("You won"); return true; } else if(board[3].equals(board[4]) && board[4].equals(board[5]) && !board[3].equals("") && !board[4].equals("") && !board[5].equals("")) return true; else if(board[6].equals(board[7]) && board[7].equals(board[8]) && !board[6].equals("") && !board[7].equals("") && !board[8].equals("")) return true; //check on the column equality if(board[0].equals(board[3]) && board[3].equals(board[6])) return true; else if(board[1].equals(board[4]) && board[4].equals(board[7]) && !board[1].equals("") && !board[4].equals("") && !board[7].equals("")) return true; else if(board[2].equals(board[5]) && board[5].equals(board[8]) && !board[2].equals("") && !board[5].equals("") && !board[8].equals("")) return true; //check the cross of the board else if(board[0].equals(board[4]) && board[4].equals(board[8]) && !board[0].equals("") && !board[4].equals("") && !board[8].equals("")) return true; else return false; } else return false; // this is left as an exercise } // end method isGameOver

I found it as following. when I create a new runnable object which in my case is the Host object, it must be followed directly with the execute method not to declare many objects then attach them to execute. any one has an explanation why that works.

I have the following server which when is created through making threads and using start method It works fine. but when use execute method on executor service object, nothing happen and no invoke for the run method in the thread to receive data from client.
package multiserver; import javax.swing.JTextField; import javax.swing.JTextArea; import java.awt.BorderLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import javax.swing.JFrame; import java.net.ServerSocket; import java.net.Socket; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import javax.swing.SwingUtilities; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.ReentrantLock; public class MultiServer extends JFrame{ private JTextField topText; private JTextArea content; private ServerSocket multiServer; private Host[] hosts; private int CLIENT_1 = 0; private int CLIENT_2 = 1; private ExecutorService pool; private Lock locker; private Condition otherClient; Thread thread1; Thread thread2; public MultiServer () { super("Multi Server"); topText = new JTextField(); content = new JTextArea(); add(topText,BorderLayout.NORTH); add(content, BorderLayout.CENTER); hosts = new Host[2];//array of two clients pool = Executors.newFixedThreadPool(2); displayMessage("Wait for connnection"); //enable server to send message to both clients topText.addActionListener( new ActionListener() { public void actionPerformed(ActionEvent e) { hosts[CLIENT_1].sendMessage(e.getActionCommand());//send message to client1 //hosts[CLIENT_2].sendMessage(e.getActionCommand());//send message to client2 topText.setText(""); displayMessage("\nServer>> " + e.getActionCommand()); } } ); setSize(300, 300);//the size of the server setVisible(true);//if remove to main method nothing appear on the screen }//end server constructor //method run server to get the connections to the server public void runServer() { try { multiServer = new ServerSocket(12346);//create server with two clients } catch(IOException e) { e.printStackTrace(); }//end server declaration try { hosts[0] = new Host(multiServer.accept()); //hosts[1] = new Host(multiServer.accept()); pool.execute(hosts[0]); } catch(IOException e) { e.printStackTrace(); } //pool.equals(hosts[i]); }//end mehtod run server //declare display message method to display on the area of the server private void displayMessage(final String message) { SwingUtilities.invokeLater( new Runnable() { public void run() { content.append(message); } } ); }//end method display message private class Host implements Runnable { Socket connect; ObjectInputStream in; ObjectOutputStream out; String inMessage; public Host(Socket connection) { connect = connection; try { in = new ObjectInputStream(connect.getInputStream()); out = new ObjectOutputStream(connect.getOutputStream()); } catch(IOException e) { e.printStackTrace(); } }//end host constructor public void run() { do { try { inMessage = (String) in.readObject(); displayMessage("\n"+inMessage); }//end try catch(ClassNotFoundException e) { e.printStackTrace(); } catch(IOException e) { e.printStackTrace(); } } while(!inMessage.equals("end")); } public void sendMessage(String message) { try { out.writeObject("Server>> " + message); out.flush(); } catch(IOException e) { e.printStackTrace(); } } } }//end class MultiServer

I found it but also I don't know why it works. I removed the set visible from the class with main method and put it in the constructor so, it is now before the call to the run server method and it worked. any one has an explanation for this.

I have the following multi threaded server for two clients, but noting appear when I run it , I don't know why. it seems in the run Server method have infinite loop

package multiserver; import javax.swing.JTextField; import javax.swing.JTextArea; import java.awt.BorderLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import javax.swing.JFrame; import java.net.ServerSocket; import java.net.Socket; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import javax.swing.SwingUtilities; public class MultiServer extends JFrame{ private JTextField topText; private JTextArea content; private ServerSocket multiServer; private Host[] hosts; private int CLIENT_1 = 0; private int CLIENT_2 = 1; private ExecutorService pool; public MultiServer () { super("Multi Server"); topText = new JTextField(); content = new JTextArea(); add(topText,BorderLayout.NORTH); add(content, BorderLayout.CENTER); hosts = new Host[2];//array of two clients pool = Executors.newFixedThreadPool(2); try { multiServer = new ServerSocket(12346, 2);//create server with two clients } catch(IOException e) { e.printStackTrace(); } displayMessage("Waiting Connection"); //enable server to send message to both clients topText.addActionListener( new ActionListener() { public void actionPerformed(ActionEvent e) { hosts[CLIENT_1].sendMessage(e.getActionCommand());//send message to client1 hosts[CLIENT_2].sendMessage(e.getActionCommand());//send message to client2 } } ); }//end server constructor //method execute to get the connections to the server public void runServer() { for(int i=0; i <hosts.length; ++i ) { try { hosts[i] = new Host(multiServer.accept(), i); pool.execute(hosts[i]); }//end try catch(IOException e) { e.printStackTrace(); }//end catch }//end for loop }//end mehtod execute //declare display message method to display on the area of the server private void displayMessage(final String message) { SwingUtilities.invokeLater( new Runnable() { public void run() { content.append(message); } } ); }//end method display message //private class Host for the clients threads private class Host implements Runnable { int clientNumber; Socket connection; ObjectInputStream in; ObjectOutputStream out; String inMessage; public Host(Socket connect, int client) { connection = connect;//get the connection socket clientNumber = client;//intialize the client number try { getStreams();//call method to intialize the socket connecitn in/out }//end try catch(IOException e) { e.printStackTrace(); }//end catch }//end Host constructor //method run to start the thread public void run() { do { try { inMessage = (String) in.readObject(); displayMessage(inMessage); }//end try catch(ClassNotFoundException e) { e.printStackTrace(); } catch(IOException e) { e.printStackTrace(); } } while(inMessage != "end"); } public void getStreams() throws IOException { in = new ObjectInputStream(connection.getInputStream()); out = new ObjectOutputStream(connection.getOutputStream()); } public void sendMessage(String message) { try { out.writeObject(message); out.flush(); } catch(IOException e) { e.printStackTrace(); } } }//end Host Class }//end class MultiServer

I got you. you mean paint called paint component which called super paint causing infinite recursive calls led to stack over flow. thanks very much

I have the following code where I call panel repaint method from the action listener of the calc button but it causes stack over flow but when I modify it to call paint component method and removing the super term, the program executes. here is the code
import java.awt.Dimension; import java.awt.Graphics; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.Box; import javax.swing.JPanel; import javax.swing.JTextField; import javax.swing.BoxLayout; import javax.swing.JFrame; import javax.swing.JButton; public class Circle extends JFrame{ private DrawPanel panel1; private JPanel panel2; private JTextField text1; private JTextField text2; private Box vertical; private Box horizontal; private double radius; private double area; String in; JButton calc; public Circle() { super("Circle"); //setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); calc = new JButton("Calc"); panel1 = new DrawPanel(); panel1.setPreferredSize(new Dimension(240, 200)); panel2 = new JPanel(); panel2.setSize(240, 30); text1 = new JTextField("0"); text2 = new JTextField(); vertical = Box.createVerticalBox(); vertical.add(Box.createVerticalGlue()); vertical.add(panel1); vertical.add(panel2); //panel two layout panel2.setLayout(new BoxLayout(panel2, BoxLayout.X_AXIS)); horizontal = Box.createHorizontalBox(); horizontal.add(Box.createHorizontalGlue()); horizontal.add(text1); horizontal.add(calc); horizontal.add(text2); panel2.add(horizontal); add(vertical); calc.addActionListener( new ActionListener() { public void actionPerformed(ActionEvent e) { if(e.getSource() == calc) { in = text1.getText(); radius = Double.parseDouble(in); area = radius * radius *3.14 ; text2.setText(Double.toString(area)); Graphics s = panel1.getGraphics(); panel1.repaint(); panel1.paintComponent(s); } } } ); } class DrawPanel extends JPanel { public void paintComponent(Graphics g) { //super.paint(g); g.drawOval(50, 50, (int)radius * 2, (int)radius * 2); } } }

My way to compile and run applet manually is as following and it worked:
1-compile the .java file with classpath option to javaws.jar
2-archive the classes files and javaws.jar in one jar file.
3-create a JNLP file with the prescribed content.
4-launch my application through javaws in cmd using the jnlp file. and worked good
but when I worked with NetBeans and despite of adding the javaws.jar as a library. every time I run the file I got UnavailableServiceException caused by ServiceManager.lookup("javax.jnlp.FileOpenService")method.
So, any help in this NetBeans topic because it is so time consuming to do everything through the cmd;

I did what you exactly said and included in the applet tag the class file an archive element with my jar file and the application was launched successfully but as you mentioned, it is the old way. it is better making JNLP file to get the privilege of accessing the client file system if needed.

I was asking because every applet in my book is using JNLP files referring to jar files but no HTML files uses jars. they only refer to class files and when I tested it myself to contain jar file inside the HTML file without JNLP file, it didn't work

I know that the simple deployment using only applet tags inside HTML causes severe security restriction for the applet on the client side. but can this simple HTML file contains .jar files inside the applet tags instead of .class files.