Java

Re: Java Parallel Port Interfacing

19-Mar-10 1:20

Fahimul7 wrote:
majority of the info is on serial ports.

Did you scroll down to the parallel port sample?

txtspeak is the realm of 9 year old children, not developers. Christian Graus

Fahimul719-Mar-10 3:24

Fahimul7

19-Mar-10 3:24

yes I did, tried using the examples given on the pdf and they did not work, i did hours of research on the internet and theres seems to be no solution, your help will be much appreciated if you can find anything

First Fit Help

Blackberry8917-Mar-10 10:15

Blackberry89

17-Mar-10 10:15

Hello
I am new to java and i have been trying to implement the first fit algorithm.
My problem is how can i can track of which memory blocks have already been assigned a job and which jobs have been assigned to a memory block.

import java.util.*;
import java.util.Scanner;

public class firstFit
{
    public static void main(String[] args) {
        
          Scanner keyboard = new Scanner(System.in);
          int[] blocks;             
          blocks = new int[3];      
          blocks[0] = 700; 
          blocks[1] = 850; 
          blocks[2] = 610; 
          //blocks[3] = 300;
          //Arrays.sort(blocks);
         
                       
          int[] jobs = new int[3];      
          
          //int index;
          
          System.out.println("Enter 3 jobs:");
          for(int index = 0; index < 3; index++){
              if(keyboard.hasNextInt()) jobs[index] = keyboard.nextInt();
            }
          
          for(int j=0; j<3;j++){
              for(int i=0; i<3; i++){
                  if(jobs[j] <= blocks[i]){
                      blocks[i]=j;
                      boolean wasAssigned[] = new boolean[blocks[i]=j];
                      System.out.println("Job" + jobs[j] + " in memory" + blocks[i]);
                      break;
                      }
                       else if(jobs[j] > blocks[i]){
                      System.out.println("Jobs in waiting queue " + jobs[j]);
                                            
                    }
                    
                }
            }       
          
        }    
}

Thank you for all help

Re: First Fit Help

TorstenH.18-Mar-10 2:14

TorstenH.

18-Mar-10 2:14

???

the System.out.println() is a simple sollution for keeping control while programming. and you can debug into your code, which allows you to check what's happening and which stuff works/throws errors.

greets
Torsten

I never finish anyth...

Java Conversions

James WG Murphy17-Mar-10 7:34

James WG Murphy

17-Mar-10 7:34

I am currently writing a program which will perform binary to decimal, decimal to binary, hexadecimal to decimal, decimal to hexadecimal conversions, 1's compliment, 2's compliment, and show the list of boolean algebra rules.

I have created the GUI however, I cannot figure out how to make the Jbuttons generate the coding needed for a binary to decimal conversion of the input in a JTextField. Please help me. The code is below:

package swing1;

/**
 *
 * @author James
 */
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import java.io.*;


public class swing {

    public static void main (String[] args) {

        JFrame frame = new JFrame("Computer Architecture Conversions");
        frame.setVisible(true);
        frame.setSize(500,500);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        JPanel panel = new JPanel ();
        frame.add(panel);

        JButton button = new JButton ("Binary to Decimal") ;
        JButton button2 = new JButton ("Decimal to Binary");
        JButton button3 = new JButton ("Decimal to Hexadecimal");
        JButton button4 = new JButton ("Hexadecimal to Decimal");
        JButton button5 = new JButton ("Library of Boolean Algebra Rules");
        JButton button6 = new JButton ("1's Complement");
        JButton button7 = new JButton ("2's Complement");
        panel.add(button);
        panel.add(button2);
        panel.add(button3);
        panel.add(button4);
        panel.add(button5);
        panel.add(button6);
        panel.add(button7);
        button.addActionListener(new Action());
        button2.addActionListener(new Action2());
        button3.addActionListener(new Action3());
        button4.addActionListener(new Action4());
        button5.addActionListener(new Action5());
        button6.addActionListener(new Action6());
        button7.addActionListener(new Action7());
    }
        static class Action implements ActionListener{

            public void actionPerformed (ActionEvent e){
            JFrame frame2 = new JFrame ("Binary to Decimal Conversion");
            frame2.setVisible(true);
            frame2.setSize(500,300);
            JLabel label = new JLabel ("Binary");
            JPanel panel = new JPanel();
            JButton b2d = new JButton("Convert to Decimal Now!");
            JTextField text = new JTextField(25);
            frame2.add(panel);
            panel.add(text);
            panel.add(label);
            panel.add(b2d);
            }
        }

        static class Action2 implements ActionListener{
            
            public void actionPerformed (ActionEvent e){
            JFrame frame3 = new JFrame ("Decimal to Binary Conversion");
            frame3.setVisible(true);
            frame3.setSize(500,300);
            JLabel label = new JLabel ("Decimal");
            JPanel panel = new JPanel();
            JButton d2b = new JButton("Convert to Binary Now!");
            JTextField text = new JTextField(25);
            frame3.add(panel);
            panel.add(text);
            panel.add(label);
            panel.add(d2b);
                
            }
        }

         static class Action3 implements ActionListener{

            public void actionPerformed (ActionEvent e){
            JFrame frame4 = new JFrame ("Decimal to Hexadecimal Conversion");
            frame4.setVisible(true);
            frame4.setSize(500,300);
            JLabel label = new JLabel ("Decimal");
            JPanel panel = new JPanel();
            JButton d2h = new JButton("Convert to Hexadecimal Now!");
            JTextField text = new JTextField(25);
            frame4.add(panel);
            panel.add(text);
            panel.add(label);
            panel.add(d2h);
            }
        }
     static class Action4 implements ActionListener{

            public void actionPerformed (ActionEvent e){
            JFrame frame5 = new JFrame ("Hexadecimal to Decimal Conversion");
            frame5.setVisible(true);
            frame5.setSize(500,300);
            JLabel label = new JLabel ("Hexadecimal");
            JPanel panel = new JPanel();
            JButton h2d = new JButton("Convert to Decimal Now!");
            JTextField text = new JTextField(25);
            frame5.add(panel);
            panel.add(text);
            panel.add(label);
            panel.add(h2d);
            }
        }

    static class Action5 implements ActionListener{

            public void actionPerformed (ActionEvent e){
            JFrame frame6 = new JFrame ("Library of Boolean Algebra Rules");
            frame6.setVisible(true);
            frame6.setSize(500,300);
            JLabel label = new JLabel ("You clicked me!");
            JPanel panel = new JPanel();
            frame6.add(panel);
            panel.add(label);
            }
        }

     static class Action6 implements ActionListener{

            public void actionPerformed (ActionEvent e){
            JFrame frame7 = new JFrame ("1's Complement Conversion");
            frame7.setVisible(true);
            frame7.setSize(500,300);
            JLabel label = new JLabel ("You clicked me!");
            JPanel panel = new JPanel();
            frame7.add(panel);
            panel.add(label);
            }
        }

     static class Action7 implements ActionListener{

            public void actionPerformed (ActionEvent e){
            JFrame frame8 = new JFrame ("2's Complement Conversion");
            frame8.setVisible(true);
            frame8.setSize(500,300);
            JLabel label = new JLabel ("You clicked me!");
            JPanel panel = new JPanel();
            frame8.add(panel);
            panel.add(label);
            }
        }
    }

Re: Java Conversions

Richard MacCutchan17-Mar-10 7:55

Re: Java Conversions [modified]

17-Mar-10 7:55

This is a continuation of your question below which you removed; please leave questions intact as the thread is now unintelligible to others viewing it for the first time.

One thing that is quite noticeable is the commonality between all the different buttons - a classic example of the need for OO - but we can leave that till later.

As a first step try removing all buttons 2 to 7 and just work on one button until you get the idea working properly. You can then add the others on top with a lot less work - and return to the OO model to do it. First thing is to decide what you want to do when the button is clicked, probably something like:

get the text from the 'input' text box
parse and validate the text to ensure it's a number
convert to an integer, based on the input format
reformat it in the output format desired
display on the 'output' label

You could develop this code in a simple console app using the Integer class to parse the input and the printf() function to display the output.

Once again, use the tutorials as they contain a wealth of information to help you learn some of the basic classes and functions.

txtspeak is the realm of 9 year old children, not developers. Christian Graus

TorstenH.18-Mar-10 2:02

TorstenH.

18-Mar-10 2:02

Lets start with simple things:

1. do not use main for greating a GUI - let another object do it for you:

public static void main (String[] args) {
 View oView = new View();
}

2. do not set up several static classes with nearly same content. Again, use objects - in this case you need 1 class for the actions which you can use serveral times. Put your classes in seperate files!

public class View extends JFrame{

// members
JPanel oPanel = new JPanel();
JButton oButton = new JButton("click");


// constructor
public View(){
oButton.addActionListener(oActionListener);  
oPanel.add(oButton);


// anonymous class
ActionListener oActionListener = new ActionListener() {
 public void actionPerformed(ActionEvent oEvent) {
  if (oEvent.equals("something")){
   //do any();
  }
  else if(...){
  }
 }
};

this.add(oPanel);

}

You could even use a method for creating all the buttons - any line just needs to be writen once:

JButton oButton = createButton("click");

private JButton createButton(final String strCommand){
 JButton oButton = new JButton(strCommand);
 oButton.addActionListener(oActionListener);
 return oButton;
}

The ActionListener can again use some object which does the conversion... for information on how to convert things you should search the net.

EDIT: please do not name classes by simular keywords - this will ruin your day someday!

greets
Torsten

I never finish anyth...

modified on Thursday, March 18, 2010 8:15 AM

JNLP Error

002comp16-Mar-10 22:37

002comp

16-Mar-10 22:37

Hello Friends
I am trying to run an applet through .jnlp and .html after changing setting in Netbeans under webStart.
When i click on .html file then only header is coming in Browser and nothing else.But When I tried same on other machine then its working there.
What could be the reason of not working on my machine?
Any idea??

Regards
Yogesh

Re: JNLP Error(Solved)

002comp17-Mar-10 0:05

002comp

17-Mar-10 0:05

Hello Guys
I got the solution.Go to java control panel and under settings remove the cache.
Thanks

Richard MacCutchan16-Mar-10 22:47

16-Mar-10 22:47

You need to add action listeners to your buttons which get fired when the button is clicked. See here[^] for a sample.

txtspeak is the realm of 9 year old children, not developers. Christian Graus

James WG Murphy17-Mar-10 2:58

James WG Murphy

17-Mar-10 2:58

I have right clicked on the buttons and added action listeners but I am not sure what coding to enter to establish new jpanels or new jframes. Sun's tutorials do not explain this matter either

Richard MacCutchan17-Mar-10 4:04

17-Mar-10 4:04

I think you may need the Internal Frame[^] class.

I would also suggest you try working through some of the swing tutorials, just to get familiar and comfortable with the components and how they fit together. If you are just using drag and drop through NetBeans it is not always clear how the various pieces interact.

txtspeak is the realm of 9 year old children, not developers. Christian Graus

David Skelly17-Mar-10 6:19

David Skelly

17-Mar-10 6:19

To show a frame you call setVisible(true).

The Sun tutorial is here:

http://java.sun.com/docs/books/tutorial/uiswing/TOC.html[^]

The tutorial is pretty comprehensive. Swing is a big toolkit, and it's not really something you can learn in an afternoon, so be prepared to invest some time learning it if you want to get the best from it.

date_time problum in java??

David Skelly16-Mar-10 23:29

David Skelly

16-Mar-10 23:29

The first thing I would do if I was you is to buy a good book on Swing programming. Sun do a very good one. If you can't afford that, there are some good tutorials on the Sun site that will lead you through the basics.

AmbiguousName16-Mar-10 2:34

AmbiguousName

16-Mar-10 2:34

hello guys....This is exactly the same code im copying from a book but yet it producing an exception saying "Can not format given object as Date"...while the author has shown the input in book...

import java.text.*;
import java.util.*;

class Date {
	public static void main(String [] args) {
		Date date = new Date();
		SimpleDateFormat sdf;
		
		
		//will show time
		sdf = new SimpleDateFormat("hh:mm:ss");
		//System.out.println(sdf.format(date));

		//will show day + date + time
		sdf = new SimpleDateFormat("dd MMM yyyy hh:mm:ss");
		System.out.println(sdf.format(date));
		
		//will show day + date
		sdf = new SimpleDateFormat("E MMM dd yyyy");
		System.out.println(sdf.format(date));
	}
}

what is wrong with this code

Re: date_time problum in java??

O.Phil16-Mar-10 3:02

O.Phil

16-Mar-10 3:02

I would say : you shouldn't name the class as Date, since it can be confusing with the Date valuetype.

...

class DateTest {

...

}

Re: date_time problum in java??

AmbiguousName16-Mar-10 3:15

AmbiguousName

16-Mar-10 3:15

thanx....

user authentication

Kunalpuranik15-Mar-10 19:04

Kunalpuranik

15-Mar-10 19:04

hello,m new in java.I m developin a login applet(client) which will send username and password to server,which will ultimately connect to database and authenticate the username and password.
how do i pass object b/w client and server???
i know the class have to implement serializable interface.
and i know the methods objectoutputstream and objectinputstream but i dont know how to actually implement them..
please help.

Richard MacCutchan15-Mar-10 22:29

15-Mar-10 22:29

Kunalpuranik wrote:
i know the class have to implement serializable interface.

This interface is for saving and restoring an object's state, it has nothing to do with client/server communication. You will need to use some socket implementation to achieve your objective.

txtspeak is the realm of 9 year old children, not developers. Christian Graus

Kunalpuranik16-Mar-10 0:32

Kunalpuranik

16-Mar-10 0:32

hey,i know the socket programming.but the socket programming is just to establish a link between client and the server.

i also know how to transfer strings between client and server as i have developed a chat application.

but what iam asking is how to transfer the object of my client class to my server end..

and the reason ive not written the code is because i dont know how to implement and thats why iam askin.
and if u want i can post my simple client server chat application code here.

Richard MacCutchan16-Mar-10 3:30

16-Mar-10 3:30

Kunalpuranik wrote:
socket programming is just to establish a link between client and the server.

Well it's a bit more than that.

Kunalpuranik wrote:
how to transfer the object of my client class to my server end.

The same way that you would transfer anything, convert it to a byte stream and squirt it down the socket.

txtspeak is the realm of 9 year old children, not developers. Christian Graus

David Skelly16-Mar-10 3:39

David Skelly

16-Mar-10 3:39

Richard MacCutchan wrote:
This interface is for saving and restoring an object's state, it has nothing to do with client/server communication

Well, strictly speaking he's right. If you want to send an object through a socket, the object must be serializable. If it isn't serializable then you have to convert its state to a serializable form (e.g. by invoking defaultWriteObject from ObjectOutputStream) before you can send it through the socket.

Think about it: the very act of sending an object from the client to the server involves saving its state at one end of the communication, and restoring it at the other.

Richard MacCutchan16-Mar-10 4:15