Threading Prevent GUI Unresponsiveness?
Jun 22, 2014HOW does threading prevent GUI unresponsiveness?
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Joda Time Threading
Nov 20, 2014I have an application that uses multiple threads to access logic. I am using joda time to compare dates because joda time is thread safe. Below is the example method I am using. My question is being that joda time is thread safe, does it matter whether or not I am using a static method rather than an instance method?
Java Code:
public static boolean isDateEqual(Date checkedDate, String targetDateString) {
boolean passed = false;
if (checkedDate != null && targetDateString != null && !targetDateString.equals("")) {
DateTime checkedDateTime = new DateTime(checkedDate);
DateTimeFormatter fmt = DateTimeFormat.forPattern("MM/dd/yyyy");
DateTime targetDateTime = fmt.parseDateTime(targetDateString);
if (DateTimeComparator.getDateOnlyInstance().compare(checkedDateTime, targetDateTime) == 0) {
passed = true;
}
}
return passed;
} mh_sh_highlight_all('java');
Servlets :: Multi Threading Mechanism?
Nov 16, 2014Is there any specific name for servlet's multi threading mechanism? I mean any technical term for it.
View Replies View RelatedJava UDP Sockets And Multi-Threading
Dec 26, 2014I have been practicing writing java code, my university course is going to cover socket programming and multi-threading.
I am presently just starting to write myself a framework for all multiplayer games I may make in the future, my aim really is simply to practice and understand better and this time, im not using an ide, just sublime text, all new grounds for me, I have a good basic understanding of the subject but I want to be fluent.
import java.net.*;
import java.util.ArrayList;
import java.io.*;
/*SMOOTH THREAD SAFE MULTI CLIENT HANDLING CLASS.
*
*This class will create connection objects when a connection is detected, these connections will run in a separate thread and update an array list in their parent class containing their last sent data
[Code] .....
Calling Multi-Threading With For Loop - Error
Feb 2, 2015I have a problem with multi threading calling with for loop. I have those two and many other classes in one jar file but n 2 different packages.
When i execute the jar file first runs the Aclass, from where i try to run multi threads. From the run() of the class RunTheGame i call many other classes which are in the same package. Like you can see from the for loop is executed the threads.
The problem is that when the second thread starts the first one is stopped this happens for all the threads, more simply when a new thread starts the old one is dead.
It seems that liken the threads uses the classes called from run() of the class RunTheGame as non multi threaded. It gives this error:
Java Code:
Exception in thread "Thread-0" java.lang.NullPointerException
at thePackage2.EClass.getWhiteRemaining(EClass.java:49)
at thePackage2.EClass.isFinal(DClass.java:84)
at thePackage2.Spiel.<init>(Cclass.java:76)
at thePackage2.RunTheGame.run(RunTheGame.java:198)
at java.lang.Thread.run(Thread.java:745) mh_sh_highlight_all('java');
All the above refereed classes are called from the from run() of the class RunTheGame . Like i understand all the threads use those classes as non thread autonomous classes.
Java Code:
public class Aclass {
private static Thread t[];
public static void main(String[] args) throws IOException {
for (int Game = 0; Game< 10; Game++) {
t[Game] = new Thread(new thePackage2.RunTheGame(aplayer, bplayer, Name, ID , Pmach));
t[Game].start();
[Code] .....
Consumer / Producer Multi Threading Scenario
Jul 9, 2014Just some questions regarding a Consumer producer program I am not understanding. Here are the two classes Below and my questions are :
1. In the main method for NamedConsumer, we created an instance of the class and call it "consumer" and we start it. Then we create another instance and we give its reference to the same variable. Doesn't this in turn destroy the original reference of the first instance we created which was started? Could we have done
NamedConsumer consumer1 = new NamedConsumer( "One", producer );
new Thread( consumer1 ).start();
NamedConsumer consumer2 = new NamedConsumer( "Two", producer );
new Thread( consumer2 ).start();
2. we called start on two difference instances of the NameConsumer class. Doesn't the "run" method need to be synchronized since two threads are hitting it?
Producer.Java
Java Code: public class Producer implements Runnable
{
static final int MAXQUEUE = 5;
private List<String> messages = new ArrayList<String>();
public void run() {
while ( true ) {
putMessage();
try {
Thread.sleep( 1000 );
[code]...
Multi-Threading - Unable To Get Outputs But Many NPEs Error
Feb 14, 2014I have been trying for days and nights , no compile error , but alot of NPEs error .......
This is my Test program
import java.util.*;
public class Test
{
public static void main (String[]args)
{
int totalShares = 0 ;
double totalCost = 0.0;
double totalProfitLoss = 0.0;
[Code] ....
I am expecting a output like this (Which I have error running:
Tracking of Stock : FCS
8 shares has been brought at $37.61
Total shares now 8 at total cost $300.88
33 shares has been brought at $36.31
Total shares now 41 at total cost $1499.11
17 shares has been sold at $42.67
Total shares now 24 at total cost $773.72
19 shares has been sold at $32.31
Total shares now 5 at total cost $159.83
31 shares has been brought at $33.85
Total shares now 36 at total cost $1209.18
28 shares has been brought at $36.37
Total shares now 64 at total cost $2227.54
20 shares has been brought at $35.49
Total shares now 84 at total cost $2937.34
At $36.00 per share, profit is $86.66
Java Socket - Client-server Communication Stuck With Multi-threading
Feb 6, 2015Firstly, my code is just a demo of my multiplayer game (2 or more players can play simultaneously) to demonstrate my problem without any extra things. I have successfully implemented peer-to-peer (P2P) communication in my game. Later, I decided to add support for client-server communication (ie a central server which is also a player) in my game. It should be much easier than P2P. Now here is the problem:
Suppose, I have 1 server and some clients (may be 1 or more clients). They all should give the following output:
Starting...
A
B
C
E
F
...
...
Done!
They all give the above output without using multi-thread. But using multi-threading, it gives the above output only when there're 1 server and 1 client. I'm using 2 threads (1 for sending, 1 for receiving) for each Socket. That means, each client has only 2 threads for communication but the server has (2 * totalClients) threads.
I've attached my full test project. So, here I'm only showing my 2 thread classes.
ReceiveThread class:
class ReceiveThread extends Thread {
private ObjectInputStream receiveStream;
private BlockingQueue<Character> queue = new ArrayBlockingQueue<Character>(Common.totalClients);
[Code] ....
Since I've attached my full test project, I'm not showing the other 3 classes. They are ServerMain, ClientMain and Common. If I've 2 clients to be connected, then I get the following output:
Server: (Runs first)
Starting...
A
Client 1 (clientID is 1): (Runs after the server)
Starting...
A
B
B
Client 2 (clientID is 2): (Runs after Client 1)
Starting...
A
They are stuck at there, even no exception. Actually, the server and the clients are stuck at the line try { ch = queue.take(); } if more than 1 client are connected. It seems that all are trying to receive data. But without using the dedicated threads, they all work as expected even for more than 1 client. Why is this behaviour? How to solve it? Note that I have used the same SendThread and ReceiveThread classes by which I have succcessfully implemented P2P communication.
About my attached test project file:
It has 5 small .java files for the classes as stated above. It is currently faulty when using additional threads. You have to change clientID variable for each client (they are described inside). But it works as expected without additional threads. To test it without the additional threads:
Comment " TODO" linesUncomment the single lines just after " TODO" linesComment the additional thread construction lines (4 lines)
Currently, for a workaround, I'm not using the dedicated threads for sending and receiving data only for client-server communication in my multi-player game. But I'm still using these threads for P2P communication. I don't know why it is and how to solve it.This is the attached test project file as described above.
Attached File(s) : Test Project.zip (4.11K)
Is It Possible To Prevent SQL Injection In Java Code?
Jul 25, 2014How can we prevent SQL Injection in Java Code?..is there any Special cases..
View Replies View RelatedUnable To Prevent Data From Overwritten
Jun 29, 2014I am trying to prevent data from being overwritten and appended instead when I save it to a file. I already set the append boolean to true on the FileOutputStream, but the data is still being overwritten. My code is below:
public class Main {
public static void main(String[] args) {
LinkedHashMultimap<String, Integer> testMap = LinkedHashMultimap.create();
//ListMultimap<String, Integer> test = ArrayListMultimap.create();
OutputStreamWriter outputStream;
testMap.put("NumberA",1);
testMap.put("NumberA", 33);
[Code]...
I performed a print statement to verify that the LinkedHashMultiMap is not replacing values with the same key (which it was not) and realized that the overwriting was occurring when I wrote the data to a file.
How To Prevent Java From Creating Object
Mar 6, 2014I just want to ask about a kind inheritance.Let say I have an interface MachineCode.I also have different classes, Binary, Hex and Octal that implements MachineCode
Question: How can I prevent java to create an Object like this:
Binary bin = new Binary();
Hex hex = new Hex();
Octal octal = new Octal();
those declaration above must be compile error,
I want to create Objects of Binary, Hex, and Octal this way:
MachineCode bin = new Binary();
MachineCode hex = new Hex();
MachineCode octal = new Octal();
JavaFX 2.0 :: SplitPane - Prevent CSS Inheritance
Jun 20, 2014I have a SplitPane, which is inside another SplitPane in the same tree hierarchy of the Scene. When I set the CSS class of the outer SplitPane, it always overwrites all CSS Settings of the inner one. How can I prevent it, so that e.g. I can assign a red divider for the outer and a green one for the inner SplitPane.
I have defined the CSS with
<code> </code>
How To Prevent Buttons From Flowing Over When The Window Is Dragged
Jul 23, 2014I'm using a BorderLayout, with 26 buttons to make up the alphabet from a keyboard. All the spacing looks great, but when you drag the screen out, everything gets jumbled. I would prefer to have everything stretch out, and keep the same positioning, or everything move towards the center still keeping the keyboard style positioning of the buttons but increasing the size of the window. Will a BorderLayout work for what I want, or should I try something else?
Currently to keep the buttons spaced apart I am keeping there preferred size to 25, and using horizontal and vertical struts to get the buttons positioned like I want.
This is how it is if I keep it the width and height 400, 400.
ex1.jpg
This is what happens when its stretched or shrunk.
ex2.jpg
This is an example of one of the ways I would prefer it
ex4.jpg
This is would also be acceptable.
ex3.jpg
How To Prevent Randomizer From Picking Same Index In Array Twice
Apr 29, 2015import java.util.*;
public class DungeonsAndDragonsRedux {
public static void main(String[] args) {
Scanner s = new Scanner (System.in);
Scanner t = new Scanner (System.in);
t.useDelimiter("\n"); // Prevent scanner from reading code after nextLine().
[code]...
I have this program that is attempting to randomly equip the player with items that are randomly chosen from a list. I don't know how to prevent it from picking the same item twice though. I also don't know how to display the items that haven't been equipped, which is another requirement of this program.
Prevent ComboBox From Being Used - Getting Null Pointer Exception
Oct 8, 2014Should the piece of code below set prevent the comboBox from being used? All it does at the minute return a null pointer exception. See I am using the same window but I have an if statement so if a condition is true then it will change certain aspects of the window. I want it to be true if it equals export which is does and it's populated fine but when I try and hide it if the condition equals import it returns a null pointer?
comboBoxEnv.setEnabled(false);
JSF :: File Upload And Prevent Refresh Calling Page
Apr 1, 2014I have a JSF page (called MainPage) with a commandButton: clicking on it, I open a modal panel with a <Rich:fileUpload> component, related to a listener in corresponding bean.
When I start to upload a file, page MainPage starts to refresh, but I would like to prevent this because it's not necessary.
I tried to "play" with <Rich:fileUpload> property values, but nothing seems to work and I don't know what to do anymore.
Here is file upload component
<rich:fileUpload fileUploadListener="#{pannelloUploadBean.uploadListener}"
id="#{cid}_input"
ajaxSingle="true"
immediateUpload="true"
listHeight="200px"
listWidth="458px">
[Code] .....
How To Prevent A User From Going Out Of Bounds In Simple Array Game
Apr 26, 2015I am making a very simple 2D array game where the player is asked what size they would like the game board to be. After entering, it displays the board and the player 'P' starts at index [0][0]. After that, they are asked for an action, which can be "up", "down", "left", "right", or "exit". I will be including some extra later (like a treasure at the end, or random obstacles), but for now this is what the game consists of.
I was instructed to "do nothing" when/if the player attempts to go out of bounds. I am trying to simply print an error, such as "Out of bounds! Try again.", then prompt the player again for an action. I even tried to make a boolean method to catch it, but to no avail.
I don't want the exception to occur at all. I just simply want the error message to print to the player and ask for another action. I would prefer not to use try/catch, or try/catch/finally since I already tried that and it still gave the exception error.This program consists of two classes. I will show the class containing the main first, then the client-server type class second.
import java.util.Scanner;
public class Driver {
public static void main(String[] args) {
World world = new World();
boolean keepPlaying;
keepPlaying = true;
boolean isOutOfBounds;
isOutOfBounds = false;
int height = 0;
int width = 0;
int x = 0;
int y = 0;
[code]....
Java Servlet :: Prevent Cross Site Script In URL
Jan 12, 2015If some one add script in my URL, I want the script not pop up, we have tomcat 6 [URL] .....
View Replies View RelatedServlets :: How To Prevent Particular HTTP Header Attribute From Browser Cache
Feb 26, 2014I am generating java script tag and javascript code in servlet and displaying it in each jsp page. i include this in every jsp in my application. I am preparing the following javascript content and diplayin each jsp
<script type="text/javascript"> BOOM.addVar (clientId = SOME universal unique ID ) </script>
the clientid will be uniqueid it gets generated every time.
Here my question is, is there any possibility the clientId will be store in browser cache or third party cache server. if yes how to prevent clientId from cache.
I don't want to prevent the whole jsp file from cache. i just want to prevent only that particular field. so that i can use advantages cache and also prevent particular header field to be cached.
Also can we prevent particular http header attribute from cache.
JavaFX 2.0 :: Predicate Bindings - How To Prevent Rebuilding Them For Each Iteration Of FilteredList
Dec 4, 2014We're twisting our minds how to use predicate bindings correctly in the real world, i. e. beyond the trivial examples for FilteredList using simply static code but no bindings!
The problem is that our predicate must be bound to a chain of BooleanBindings, of which the final term needs the item injected into the predicate by the FilteredList. Example see purple code:
BooleanBinding a = ...
StringBinding b = ...
ObjectBinding<Predicate> c = Bindings.createObjectBinding(() -> item -> a.or(b.isEqualTo(item.someProperty())).get(), a, b); // Ugly: No "Bindings" style!
myFilteredList.predicateProperty().bind(c);
This code has an ugly smell! It first looks like "Bindings" style, but in fact is plain old lamba mostly! But it also is slow: The code enforces splitting of a and b into separate bindings as it enforces rebuilding the chain a.or(b.isEqualTo(...)) for each single iteration of titem in turn. That induces unnecessarily creating and garbage-collecting Bindings "on the fly", which is not how Bindings are intended -- they shall be created once and simply update their value instead of getting replaced themselves to prevent wasting CPU cycles and keep memory clean.
How to do Predicate Bindings correctly (i. e. without temporarily building Bindings for each "t") ...
JSP :: Generate Hashtable And Display Its Key Value Pairs Back To Browser - How To Prevent Timeout
Jun 24, 2004I have a jsp page that generate a hashtable and display its key-value pairs back to the browser. The problem is that it takes on an average about 15 minutes to build this hashtable, and as a result, I always get a timeout error. What can I do to avoid getting the timeout error without changing the server configuration for timeout
View Replies View RelatedSwing/AWT/SWT :: Code Prevent Cursor From Moving When Inside A Cell Of JTable
Jun 24, 2014Tried creating a simple sample but all works as expected.
The following code prevents the cursor from moving when inside a cell of a JTable.
public void keyPressed(KeyEvent e) {
if ( (e.getKeyCode() == KeyEvent.VK_KP_LEFT) || (e.getKeyCode() == KeyEvent.VK_KP_RIGHT)
|| (e.getKeyCode() == KeyEvent.VK_RIGHT) || (e.getKeyCode() == KeyEvent.VK_LEFT) )
{
//Do nothing
e.consume();
}
}
});
When editing a cell, the existing code would use the right/left cursor keys to move from cell to cell as opposed to from character to character when editing a cell. I planned to override the functionality by tossing in the above code as a test to see if it stops the functionality before I override it.
After placing in the above code, the above functionality no longer occurs, but now the cursor moves within the cell as I wanted which is to move from character to character instead of cell to cell. Its great it works, but it really shouldn't. Essentially the default behavior has been restored when it should have really disabled the left/right keys.
I assume there is some underlying class someplace that is doing something to affect the behavior. Since a sample can't be provided I am wondering in what scenarios would the e.consume() restore default functionality?
JSP :: Prevent Dot Matrix Printer Scrolling Entire Sheet After Printing Page As Receipt
Jul 25, 2014i am developing a web application and uses jsp page to print a payment receipt.
everything works good, but printer scrolls complete sheet after printing first receipt. so need scroll back manually every time i print a receipt.
So, how to stop printer from scrolling entire sheet.
JavaFX 2.0 :: How To Prevent User From Leaving Tableview Editing Cell In Case Of Errors
May 14, 2014I have a TableCell that will hold numbers in a tableview. All is working work nicely, but I want the following behavior:
- when the user begins to edit such a cell, if it doesn't enter a number, the cell will not call commitEdit, but rather display a red border and prevent the user from changing the focus to anything else until he either: enters a correct number or presses ESC.
I don't know how to keep the user in that editting cell if while he has an incorect number. Currently he can click other row/control and he will break the edditing state. I repeat, I don't want the user to be able to click on any row/control until he has a correct number.
Here is my cell implementation:
public class EditableIntegerCell extends TableCell<Person, Integer> {
private TextField textField;
@Override
public void startEdit() {
if (!isEmpty()) {
super.startEdit();
createTextField();
setText(null);
[Code] .....