Canvas inside applet - Java Discussion Boards

Please do not post the same question in multiple forums.

Just say 'NO' to evaluated arguments for diadic functions! Ash

Hi,

I have 3+ years of experience as a software Engineer in Java,J2EE concepts ,
developing the web-application and ERP domain modules,
I have currently offer in two companies for separate in two different domain
projects. Below are the details...

Offer 1 - The role is of an engineer in developing the web-applications
using J2EE concepts (springs, hibernate,and JSF) Client --Reddy Labas

Offer 2 - The role is of an engineer in developing the projects using the
tool called Identity Management (J2EE concepts as backend) Client-JPMorgan.

I am little confused to choose which offer and how it is going to be the
best thing in my career /future (job Resources) view.

Am seeking your valuable inputs on which one would be a better offer.

Thank you!

Don't post in multiple location. It makes it difficult to keep related discussion together, and you could end up with duplication or 2 discussions ongoing about the same thing.

This is currently being answered here;

http://www.codeproject.com/Questions/117507/Best-Option-for-Choosing.aspx[^]

Dave
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CPRepWatcher now available as Packaged Chrome Extension, visit my articles for link.

krishnareddy036 wrote:
Offer 1 - The role is of an engineer in developing the web-applications
using J2EE concepts (springs, hibernate,and JSF) Client --Reddy Labas

Per this description you would be using Java and associated common frameworks and idioms.

krishnareddy036 wrote:
Offer 2 - The role is of an engineer in developing the projects using the
tool called Identity Management (J2EE concepts as backend) Client-JPMorgan.

Per this description you would be using a specific vendor tool.

Thus in terms of a career in programming the first is better.

However there could be other criteria.

For example do you want to remain a programmer? If not then which position seems to allow a better chance to move into management?

Another example do you want to use other languages? If yes then which job is more likely to allow you to do that, for example is one more likely to allow you to learn SQL?

You might also want to look into what stage the project is on that you would be working on. Maintenance programming on an existing project for someone with your experience might not be as enjoyable as a new project or one that is relatively new. Along those lines you might ask, of both companies, what additional programming possibilities might exist in a year from now.

when we call servlet from a JSP page .. explorer/program moves to servlet page .... Such in my scenareo i have JSP form that on submiting call servlet to retrieve data from XML .. But problem is that . i like that on submitin form servlet runs in background without changing page to servlet page ... like thread in background .... SO PLZ ANY IDEA OR SUGGESTION !!!!
THANKS T ALL HELPERS ...

khurram_shahzad wrote:
SO PLZ ANY IDEA OR SUGGESTION !!!!
THANKS T ALL HELPERS ...

Don't shout!

Just say 'NO' to evaluated arguments for diadic functions! Ash

From what I think I read in your question, you want to do Ajax. This will allow you to put a request out to the servlet and process the result with Javascript inside the HTML without changing the actual browser page. Try jQuery to get this to work.

If you do not know what Ajax or jQuery are, you first need to do some reading. There is enough info on this on the internet.

Hi i've created a canvas for game and an applet which contains this canvas and can communicate with my database. But when canvas goes into the game loop my applet doesn't respond anything i can't even close it. Also in my canvas' constructor method i make it's background black but it doesn't work either. Here is the code for 2 classes. And for now game loop is empty but i tried it with simple game loop which runs at 25fps and sleeps when needed.

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferStrategy;

public class GameCanvas extends Canvas implements Runnable{
    private Graphics2D graphics;
    private BufferStrategy bufferStrategy;
    private boolean gameRunning;
    
    public GameCanvas(){
        setBackground(Color.black);
        setSize(300, 300);
    }
    
    public void initGame(){
        createBufferStrategy(2);
        bufferStrategy = getBufferStrategy();
        graphics = (Graphics2D)this.getBufferStrategy().getDrawGraphics();
        gameRunning = true;
        Thread t = new Thread(this);
        t.run();
    }
    
    public void run(){
        gameLoop();
    }
    
    public void gameLoop(){
        while(gameRunning){
            
        }
    }
    
    public void update(){
        
    }
    
    public void drawScreen(){
        graphics.clearRect(0, 0, this.getWidth(), this.getHeight());
        //some drawings;
        if(!bufferStrategy.contentsLost())
            bufferStrategy.show();
    }
}

import java.sql.*;
import javax.swing.JApplet;


public class DatabaseApplet extends JApplet{
	Connection con;
	
	static{
		try{
			Class.forName("com.mysql.jdbc.Driver").newInstance();
		}catch(Exception e){
			e.printStackTrace();
		}
	}
	
	String url = "jdbc:mysql://127.0.0.1:3306/players";
	String name = "root";
	String password = "root";
	GameCanvas gameCanvas;
	
	public void init(){
		setSize(300, 300);
		add(gameCanvas = new GameCanvas());
		try{
			con = DriverManager.getConnection(url, name, password);
		}catch(SQLException e){
			e.printStackTrace();
		}
	}
	
	public void start(){
		gameCanvas.initGame();
	}
	
	public void destroy() {
		try{
			con.close();
		}catch(SQLException e){
			e.printStackTrace();
		}
	}
	
}

public void gameLoop(){
    while(gameRunning){

    }
}

I cannot see how you get out of this loop, nor how it ever releases control.

Just say 'NO' to evaluated arguments for diadic functions! Ash

First of all thanks for the answer. I'm running this game loop in another thread so shouldnt operating system take care of giving other threads clock time? And as i said before if i do something like Thread.sleep(freeTime) or Thread.yield() it doesn't work either. I tried it inside html and surprisingly it makes background black there. Also can you suggest how can i make a canvas game inside applet because there must be a game loop similar to this.

Well I've copied your code and run it up in my IDE and that little closed loop really seems to block everything. I think you will need to redesign how you are doing this, although I can't offer any suggestions about how to do this in an applet without going back to the Tutorials[^].

Just say 'NO' to evaluated arguments for diadic functions! Ash

I found a solution. When i use t.start() instead of t.run() it works correctly. Thanks for your replies again.

hi i have worked in VB/C# where i created LAN enabled applications like apps for record handling and MIS/ERP solution type, now i have switched to java so i want to know a few queries as:

1. Do we have to go JSP/EJB for LAN applications or i can make them in core Java too.

2.if,its possible to create application like that in core java ,what kind of classes/packages i need for them(other then java.net) and 3rd party api's for simple working?

3. how can such application be going to interact with each other or do i need threads (thread executions) to make it understand about every process going between diiferent client and one server?

4. Is it not possible to achieve such facility with DB connection call with diff server ip/port instead of making the app to listen for its server and then work ?

5.in Above,, which one will going to be smooth in between them?

i know its too much in one go but if you can please solve my any query first you like Cool | :cool:

In this world only the hardwork with smart approach wins.....

Alok sharma ji wrote:
1. Do we have to go JSP/EJB for LAN applications or i can make them in core Java too.

No. They provide a framework, you can go lower and use RMI to call the server and build the server using normal classes. Or you could go lower still and open TCP sockets and send your data back and forth that way.

Alok sharma ji wrote:
2.if,its possible to create application like that in core java ,what kind of classes/packages i need for them(other then java.net) and 3rd party api's for simple working?

Yes. Easy as falling out of a tree. Write the classes you want and bang. I would suggest developing a first cut as a single process, with the business funtionality protected by a facade that only returns basic types. Then you can put the comms in the middle.

Alok sharma ji wrote:
3. how can such application be going to interact with each other or do i need threads (thread executions) to make it understand about every process going between diiferent client and one server?

I would suggest that you would want to handle each client on a seperate thread, otherwise you'll soon hit performance problems. Concurrency isn't magic, it is relativly easy to do.

Alok sharma ji wrote:
4. Is it not possible to achieve such facility with DB connection call with diff server ip/port instead of making the app to listen for its server and then work ?

I think the question here is about the backend data tier. You should use a JDBC defined connection then the DB can be configured at deployment. I would not expose the DB to the client.

Panic, Chaos, Destruction.
My work here is done.

or "Drink. Get drunk. Fall over." - P O'H

thanks for your answers, on the point 4 i was thinking of passing the ip of DBserver (instead of passing a usual localhost) so the application connects itself their with no sweat, but i think thats a too much of wishful thinking Smile | :)

Anyone here doing any serious Android dev?

Should CP start a forum just for it?

Humble Programmer

No i don't think we need a dedicated forum, after all it is just Java. Failing that you could always use the Mobile forum.

If you search the Articles for Android, you will find some others who are developing on the platform.

Dave
Find Me On: Web|Facebook|Twitter|LinkedIn

CPRepWatcher now available as Packaged Chrome Extension, visit my articles for link.

I am trying to connect to oracle database installed in unix from java program using jdbc.

I get this error:
java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:164)
at Conn.main(Conn.java:6)
Exception in thread "main" java.sql.SQLException: No suitable driver
at java.sql.DriverManager.getConnection(DriverManager.java:545)
at java.sql.DriverManager.getConnection(DriverManager.java:171)
at Conn.main(Conn.java:11)

I know I need to tell the path to the oracle driver, but I am not sure how to set it. I dont have a CLASSPATH environment variable. Do I need to create it? Please help

itsh11 wrote:
I dont have a CLASSPATH environment variable. Do I need to create it?

It would seem like a useful start. It's some time since I worked on UNIX but you just need to set a shell environment variable and export it; check the man pages for whichever shell you are using.

Just say 'NO' to evaluated arguments for diadic functions! Ash

No, you do not need to set up the CLASSPATH environment variable, you can use the -classpath parameter when you run java, which is the way I always do it. I feel more "in control" when I set the classpath explicitly rather than relying on an environment variable which may or may not be right.

There are other ways to do it (e.g. put the driver jar into jre/lib/ext) but they can get a bit messy when you need to worry about different versions.

i want to make a program that he can do this table:

can any one help me
to write code in j2me for this program

program :

1-add contact (mail).
2-record voice message (one minute).
3-send voice massege to contact.

please help.

the program connect to web server and send the message as mail
Rose | [Rose]

So here are some steps to do that:

1. Download Java SDK from Oracle
2. Install an IDE (Eclipse / Netbeans or whatever you like)
3. Read some about the Java ME
4. Start coding

And then when you encounter a specific issue or error post it here and we will help you allong.

import java.util.*;
import java.text.*;
import javax.swing.*;
class Lab4Part2{
public static void main (String[] args) {
String ex1;
double sum, F, a=0, b=0;
JFrame myWindow=new JFrame();
myWindow.setSize(500,400);
myWindow.setTitle("Calculator");
myWindow.setVisible(true);
myWindow.setLocation(600,200);
ex1=JOptionPane.showInputDialog(myWindow, "Enter an expression");
F=Double.parseDouble(ex1);
sum=(a+B);
JOptionPane.showMessageDialog(myWindow, "The sum is "+sum);
}
}

I need some help I keep getting an error when I try to run it on JGrasp. I have no clue what I'm doing wrong and for that matter I don't know what I have to do next if I am doing something wrong or not. However I'm trying to create a program where there are one input dialog that asking for the expression in "a+b" form like I would have to input "1+2" and then the second dialog would be a message giving the answer to that 1+2 which would show the message of 3. The program compiles fun and runs fine however whenever it asks me in the input dialog for an expression and I put "5+15" the message dialog shows an answer of 0.0 which is wrong as it should be 20 or 20.0 so basically at this point I don't know what I'm doing wrong or what I should do next as I am only a freshman in college and is only taking beginners object oriented programming using Java but anyways Thanks for helping. One last thing, I asked my teacher what I should do and she said I should use the substring and indexOf methods but she never told me how so I'm curious to what I should do and I need help with this too please and thank you.

PS. I tried Double.parseDouble method however I realized I can't parse more than one variable therefore that wouldn't work.

There's really a lot of things which are wrong with your code:
1) To calculate the sum, you add a and B, but they were never assigned any value except 0. And 0 + 0 is 0.
2) B doesn't exist, you declared b. So your program shouldn't even compile (I guess this is a typo error)
3) showInputDialog returns a string. You have to parse the string in order to extract the two values needed for the sum. But what if the user enters something else than a sum (like garbage text). You never check if the string is valid.
4) In fact you try to parse the string and store the result in F but it doesn't work this way: your string is not a double, because it contains a "+". So, first thing to do is to tokenize the string in order to retrieve the two operands.

Please, next time you have to post code, use the pre tags it makes the code much more readable (as explained in the posting guidelines that I suggest you to read).

Cédric Moonen
Software developer

Charting control [v3.0]
OpenGL game tutorial in C++

As explained above, let me make it a bit more clearer for you

import java.util.*;
import java.text.*;
import javax.swing.*;
class Lab4Part2{
public static void main (String[] args) {
String ex1;
double sum, F, a=0, b=0;
JFrame myWindow=new JFrame();
myWindow.setSize(500,400);
myWindow.setTitle("Calculator");
myWindow.setVisible(true);
myWindow.setLocation(600,200);
ex1=JOptionPane.showInputDialog(myWindow, "Enter an expression");
//F=Double.parseDouble(ex1);  You cannot parse the whole string as double since it has 
              //a '+' sign and besides the user might enter other invalid Characters
//Validate that the user entry is in the valid form so check the input to see if there 
      //is anything else besides numbers and + sign in the input, something like this
//"^\\d+[\\+]\\d+$" is a regex to validate the i/p, try researching on your own to figure 
              //out
if(Pattern.compile("^\\d+[\\+]\\d+$").matcher(ex1).find()) {
  String[] inputnums = ex1.split("+");
  a = Double.parseDouble(inputnums[0]);
  b = Double.parseDouble(inputnums[1]);
}
else
 //throw an exception informing the user that the i/p is incorrect.

//sum=(a+B); mind the case
//sum=a+b;
JOptionPane.showMessageDialog(myWindow, "The sum is "+sum);
}
}

--Modified the regex

I are n00b.

modified on Friday, October 8, 2010 12:08 PM