Observer Controller Pattern (MVC)
Dec 10, 2014
Model View Controller design pattern I completely understand then I was told about the observer controller pattern. After reading and reading I and watching video clips on youtube explaining it I have a question:
Isn't the actionListener the observer so to speak. It is firing whatever action it is told to do and dynamically updates the program to.
Example, I have a JButtons and a JTextArea. I press the button and it gives the current stock price of some stock, I press it again it refreshes. Sounds like an observer to me... Am i on the right track here?
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Sep 12, 2014
create an application following the MVC pattern. My frame is composed of a JTable with some JComboBox and classic next/previous buttons to page the table. The table shows data of current accounts of the members of a family. My problem is figuring out how the controller interacts with the view, for example to enable / disable buttons or reset and reload the data in the comboboxes. In the view class all the graphical components are private instance variables. What is the best approach to ensure that the controller can act on them?
I need to create in the view public methods to act on each component like getSelectedItemAccountCombo, getSelectedItemYearsCombo, getSelectedItemMonthCombo, populateAccountCombo (ArrayList <String> list), setNextButton (boolean b) ... and so on (I think that the methods would be many ...) This approach does not convince me because I think that the class is fouled by procedures that should be in the controller class.
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Nov 16, 2014
I am unable to connect my javafx scene to mysql database. I get a java.lang.NullPointerException every time. I tried searching everywhere possible but no answers available. This is the Person class (super class for Teacher class):
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
[code].....
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Sep 11, 2014
I've got 2 view classes with their own viewcontroller. In view 1 i'v got a combo box with a observablelist wicht show me some values.
What i want is to put an new value to the combobox through the controller of view2.
When i make the observablelist static it works but i think that isn't a nice way.
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May 24, 2014
I have used jsp's to passing request to the servlet or controllers. but we can also pass request from javascript using ajax and sending data using json.
what is the good approach and why? or does it depends on the situations? is yes, what kind of situations?
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Sep 25, 2014
I do Java for decades, but am a FXML beginner. Currently I do FXMLLoader.load(fxmlFile) in Application.start(), which is working well. My Application instance is creating a background thread in Application.init() which feeds several custom application properties with incoming data taken from a remote model (wrapping a sensor hardware). Some of my windows shall later be able to access those properties. So the question is: How can I inject my Application instance into the FXMLLoader-created controller instances auto-bound to the FXML-created Scene instances?
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Jun 24, 2014
I used the SceneBuilder to create an applications and it works quite well. Now I got a problem to set the pref. size of a ScrollPane to the size of the app.
I want to install a binding between the scroll pane's pref. size and the stage's pref. size. Since the scroll pane field reside in the FXMLController class I need a way to access this field.
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May 6, 2014
I am working on an project in which some data needs to be received through socket , do some processing on it and then store on the database. After that it will display on GUI. GUI should be updated automatically.
I am able to implement basic model in which data is storing in the database and displayed then on the GUI. I tried to implement MVC design patter as well.
Now i need to create a GUI which can be used by several users at a time means several jvm session for the GUI. I got struck at this point.
Some detail: i have one jvm session in which i am receiving , processing and storing the data. Now i want to fire an alert whenever any new entry is made into the database. Also each time new GUI is opened it should be registered with the model so that model send updated data alert to all this users.
When i am trying to open several GUI and trying to register with the Model then it is not increasing count of registered user. For each time it is showing 1 count only and whenever a new entry is made count is showing 0. Is it because both are running in different jvm sessions ?
Some code for the model which is running in different package and jvm
GUI..
private void runApp() {
//some gui code
WindowListenerClass windowListener = new WindowListenerClass(this);
frame.addWindowListener(windowListener)
//registering viewer with the model
Model.setNewAlarmEvent(this);
tableModel = windowListener.getDefaultTableModel();
[Code] .....
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Jan 7, 2014
When I hit the url at the first time my call goes to the spring controller and sets the userDetails objects in the modelAndView.addObject("userDetails", userDetails.getUserDetails()) and returns the userDetails.html page. if I click any link in the same page i want to pass same (userDetails) object thru javascript or jquery and calls the another(controller) method and returns the same (userDetails.html) page.
It means how can I pass the java object thru javascript or jquery and calls the controller. If I get the same object in my controller i can avoid calling the db again.
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May 12, 2015
I need to pass advanced object into controller from JSP page, but I always get null result.It's a controller method:
Java Code:
@RequestMapping(value="admin-user-edit", method=RequestMethod.POST)
public ModelAndView editUser(@ModelAttribute(value="user") UsersEntity user)
{
if (null == user)System.out.println("User is null");
else
System.out.println("User name = " + user.getName() + " | Users id = " + user.getId());
ModelAndView view = new ModelAndView();
return view;
} mh_sh_highlight_all('java');
And this is a JSP page snippet. I need to choose some user from user list and pass it to controller.
XML Code:
<c:forEach var="user" items="${user_list}">
<tr>
<td><c:out value="${user.id}" /></td>
<td><c:out value="${user.name}" /></td>
<td><c:out value="${user.login}" /></td>
<td><c:out value="${user.status}" /></td>
[code]...
I tried to pass it through HttpServletRequest argument but all the same.
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Sep 29, 2014
I have a controller that on the basis of commands (formaction and subaction) dispatch requests to different jsp pages. But somehow when I am debugging my application, I can find duplicate request coming to the controller, so one jsp page does load twice. I am not sure from where the duplicate request is generating.
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Jan 30, 2014
I use a bluetooth module (dwengo) in combination with a microcontroller (PIC16F877A). I want write a bluetooth client program in java to communicate with the microcontoller. Examples of clients on internet do not work or give errors I cant'n resolve. There is one program ( SampleSPPClient ) that give no errors and shows the bluetooth devices present.
But when I choose my bluetooth module I got an error (Device does not support Simple SPP Service). I think that I have to use an other service of bluetooth but I don't know how to implement. Here is the program I tried to use ....
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.Vector;
import javax.bluetooth.DataElement;
[Code] ......
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Dec 8, 2014
Sometimes models needs to access blocking devices, like network cards, databases, files, and so on. This should be done by worker threads or services. But who is in charge of that? The controller or the model itself? I tend to say it is the model, as only the model knows about the fact that it accesses a blocking object. On the other hand, it is said that a model should be a POJO, so it would be the controller's job. Is there a best practice or general design rule?
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Apr 21, 2015
I have created this program that outputs
1
12
123
1234
12345
123456
I tried looking up some ways to create spaces in between each number, but I failed miserably. Here is what I have right now.
public class Iterations {
public static void main(String[] args){
for(int i=1;i<=6;i++)
{
for(int j=1;j<=i;j++)
System.out.print(j);
[Code] ....
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Mar 10, 2014
I want to know how to print this type of pattern when a name is given ???
Example:
name given TEJA
Capture.PNG
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Jan 12, 2015
I am able to get Cpu speed using my GetProcessorSpeed method and It returns this output 1796. How can apply this pattern "#.##". I am trying something like this.
Format formatter=new DecimalFormat("#.##");
formatter.format(MainClass.GetProcessorSpeed());
label2.setText(formatter.toString());
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Jan 11, 2014
I was reading head first java and the author told to read head first design pattern next.
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Apr 24, 2015
Why the following string fails the test below:
@Pattern(regexp = "^[_a-zA-Z0-9-]+(.[_a-zA-Z0-9-]+)*@[a-zA-Z0-9-]+(.[a-zA-Z0-9-]+)*.(([0-9]{1,3})|" +
"([a-zA-Z]{2,3})|(aero|coop|info|museum|name))$", message = "Not a well-formed email address")
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Jul 3, 2014
I have code which validate code enter by user
the requirement say the maxlength=2 and minlength=1 and is a string
the user can enter code as follows
00
A1
HH
12
10
09
I have this Java Code:
public boolean isValidPattern(String s_value, String s_pattern) {
boolean flag = false;
if (Pattern.matches(s_pattern, s_value)) {
flag = true;
}
return flag;
[Code] ....
My problem is when user put
A1 AM geting error
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Jul 2, 2014
So I'm studying for a test i have coming up on recursion so i was playing around with it. I ended up making a pattern of stars that look that such :
*
**
***
The code i had for that was
public void makePattern(int size){
if(size == 0){
System.out.println();
}
else if(size > 0){
System.out.print("*");
makePattern(size - 1);
}
}
I was wondering if i wanted to expand on this and make it do something like
*
**
***
**
*
What condition would i have to add i was struggling trying to figure it out...
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Apr 24, 2014
I am in an intro programming class and we got assigned a problem for creating a super class with about a dozen sub classes for generating a random word(via WordGetter class) and then comparing that word to a variety of different patterns(like: does the word contain "re"). We were given the super class which looks like this...
public class Pattern {
public boolean matches(String text) {
return true;
}
public String toString() {
return "(TRUE)";
[code]...
and from this class, we have to write subclasses that override those three methods. I am struggling to understand inheritance and I am not really sure where to even start. Here is the instructions for the first sub class we need to write...
"CONTAINS" SUBCLASS
Constructor: The constructor accepts a String named ‘letters’.
Matches: This pattern matches any text that contains at least one occurrence of each ‘letter’.
toString: produces the text “(CONTAINS <LETTERS>)” where <LETTERS> is the ‘letters’ string.
getLetters(): this method must return letters.
equals(Object): careful on this one. Two Contains are equal if they have the same letters (order is not relevant).
(Example):
Pattern p = new Contains(“re”);
boolean f1 = p.matches(“renew”); // f1 is true
boolean f2 = p.matches(“zoo”); // f2 is false
String s = p.toString(); // s is “(CONTAINS re)”
boolean f3 = p.equals(new Contains(“er”)); // f3 is true.. really..
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Feb 21, 2015
I'm trying to make a triangle which should look like this. But I cant seem o figure it out.
1
2 1
4 2 1
8 4 2 1
16 8 4 2 1
32 16 8 4 2 1
64 32 16 8 4 2 1
128 64 32 16 8 4 2 1
This is the code I have written so far.
public class TestProgram
{
public static void main(String[]args)
{
for (int columns=0; columns<=8; columns++)
{
for (int rows=columns; rows>=1; rows --)
{
System.out.print(rows+ " ");
}
System.out.println();
}
}
}
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Jun 27, 2014
I'm having a hard time implementing a simple composition example in Java:
Java Code:
public class CompositionPattern {
public static void main(String[] args) {
Udp udp = new Udp();
Imap imap = new Imap();
udp.startService();
imap.startService();
[Code] ....
The above won't compile. It says "The method supportsMe() is undefined for the type Object". I understand that I stored parent as an Object. But in reality it is not simply Object, but a Udp object or Imap object. The point is to make Responder generic. I don't want to have to cast the Object to Udp or Imap. Any solutions so I can keep this generic?
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Apr 21, 2003
I have heard about using patterns in core java.Is it possible?If yes, how?
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Mar 27, 2015
I need selecting which design pattern to use in my case.
I am creating a list of objects "items" to be presented in a list for the user to choose from, all objects have a title and a check box. Some objects have additional textbox for user input, some objects have additional image for illustration, and some objects have additional textbox and image as well.
I read and saw online videos but not sure if my selection "Factory Design Pattern" is the best match.
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Jul 16, 2014
The program I'm working on is supposed to read input from a file and using recursion, print the pattern of asterisks for each value until the value is either < 0 or > 25.For example, if the value was 4, the pattern would look like this
*
* *
* * *
* * * *
* * *
* *
*
The values are stored in a file entitled prog3.dat which looks like this
4
3
15
26
0
I've never used recursion before and haven't been able to find anything showing how it would work with this particular type of problem.Here is what I've been able to come up with so far, but I'm having problems still which I will show following the code.
import java.util.Scanner;
import java.io.*;
public class Program3 {
public static void main(String[] args) throws Exception {
int num = 0;
java.io.File file = new java.io.File("../instr/prog3.dat");
Scanner fin = new Scanner(file);
[code]...
It appears to be reading the file correctly, but is only printing the top half of the pattern. Also, like I said, I'm not very familiar with recursion, so am not sure if this is actually recursion?
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