Threads Share Static Variable But Behave Differently With Respect To It
Apr 26, 2015
Here is my code. Obviously this doesn't do a lot but that's only because I abstracted out the problem so there are not many lines to decipher.
Java Code:
import java.util.Scanner;
class threadOne extends threadTwo {
public static void main(String[] args) {
threadTwo threadTwoObj = new threadTwo();
threadTwoObj.start();
while (!userInput.equals("exit")) {
[Code] ....
What its supposed to do: When the user returns "exit" in the console it is supposed to break out of both while loops in both threads.
What it actually does: breaks out of the while loop in threadOne and not in threadTwo.
Basically the idea is to have a thread running doing computation and another thread able to query it for updates or interact to make changes to the flow. This will be useful, among other ways, for the sorts of problems where finding a solution is easy but where a better solution can always be found with more time. So for example finding directions on a map. Its easy to find a solution, but if you search longer you can find a faster route, if you search longer still than faster still.
One class having two method one as static n another as non-static, 2 threads are there t1 is accessing the static method and t2 the non-static method is it possible n both are sharing the same object.
I now we have two kinds of lock one is object level lock and another is class level lock
I have a multithreaded application. I have a Logger class with static methods that I use across threads. Would it behoove me to add the synchronized keyword to the static methods of the Logger class since I use this class statically in different threads?
I am trying to call an actionListener which is shown below in my PSVM :
class testMenuItemListener implements ActionListener { public void actionPerformed(ActionEvent arg0) { getContentPane().removeAll(); createPanel(); getContentPane().add(panel1); //Adding to content pane, not to Frame repaint(); printAll(getGraphics()); //Extort print all content
[Code] .....
I get the following error :
Frame.java:409: error: non-static variable this cannot be referenced from a static context menuItem1.addActionListener(new testMenuItemListener());
I am trying to add a field (called special) to a hibernate table. I am copying existing code (related to the NAME field) so I don't have to figure this out from scratch. I am getting the error
"[ERROR] C:VOXvoxware-1.1.13voxwarevoxware-implsrcmainjavacomvoxwareimplflowVoxFlowConfiguration.java:[213,38] error: non-static variable special cannot be referenced from a static context".
Line 213 is in public void mergeFrom, the actual line is "special = VoxFlowConfiguration.special;" I don't understand why Java thinks special is a "non-static" variable but it doesn't have a problem with the other variables (such as name, orderShow)
I am trying to call an actionListener which is shown below in my PSVM :
class testMenuItemListener implements ActionListener { public void actionPerformed(ActionEvent arg0) { getContentPane().removeAll(); createPanel(); getContentPane().add(panel1); //Adding to content pane, not to Frame repaint();
[Code] .....
I get the following error :
Frame.java:409: error: non-static variable this cannot be referenced from a static context menuItem1.addActionListener(new testMenuItemListener());
The error said : Non Static Variable TAShaReport Cannot referenced from a static context
I just want to put the output in the TextArea
Here is the code :
public static String DeduplicateFiles(String myFolderLocation) { try { HashSet<String> newset = new HashSet<>(); File folder = new File(myFolderLocation); //Directory where the files are located File[] listOfFiles = folder.listFiles();
This is a someway special question, because I am using jmonkeyEngine.
But the topic is simple:
I have 2 classes:
public class Spielbrett extends SimpleApplication { public static void main(String[] args) { Spielbrett app = new Spielbrett(); app.start(); } @Override public void simpleInitApp() {
[Code]...
as the main class and a second class for the chips:
public class Spielstein { public Spatial stone; public int player; public int team; private AssetManager assetManager = Spielstein.getAM(); //THIS IS THE PROBLEM public Spielstein(int t_player, int t_team){
[Code]...
My problem is: I can't access getAM() from the first in the second class. If you know why I would be glad for an answer.
One of my friend asked me that which will load first static variable or static block ? My answer was to static variable.. So he gave me two program and said to differentiate between them
1st program
public class Test { public static void main(String args[]) { System.out.println(Test.x); } static { System.out.println(Test.x);
[Code] ....
Output of this :
90 90
I tried to decompile the byte code and found it's same for both the above equation. How to differentiate between them. I am confused when the static variable will initialised.
I wrote a code to use static class. But, when I call the class in a outer class but, it gives an error. Is it mandatory to have a static class should have static variables when we declaring them??
public class StaticClassMain { static class Sub{ String str="Example 1"; } public static void main(String[] args) { System.out.println(Sub.str); } }
I have a class Tree in which all the methods to build a tree are in place. But however I would want variable of by Tree which is pointing to the last node being added to the tree.
So basically every time you keep adding a node to the tree you tail pointer gets updated to point to the last node. I have this so far.
public class NonEmptyTree implements Tree { private Tree left; private int data; private int leftleafCount; private int rightleafCount; private Tree right; private Tree tail; // This variable must be shared by all the object. There needs to just one tail pointer to the tree. public Tree insert( data ) { tail = // gets updated every time when new node gets added.
Sandwich class. I have thus far completed creating a sandwich class with a seperate sandwich Tester class to run with it. (this is according to the assignment). Now I must create Static variables for the sandwich class:
Add two static variables to the Sandwich class to count how many sandwiches are sold and how many slices of tomato are used. Initialize each to 0.Where do you add code to increment the sandwich counter? Determine this and then add code.
public class Sandwich { static int numOfSold = 0; static int slicesUsed = 0; private String meat; private int numOfSlicesOfTomato; private boolean lettuce;
How can i take run time value for static final variable...my lecturer said first time assignment is possible for declared final variable but in my case it shows compile time error..I'm placing my program below with error message
class Sample { static final String cname; void print() { System.out.println(cname); } public static void main(String args[]) { cname=args[0]; Sample s=new Sample(); s.print(); } }
Sample.java:11: cannot assign a value to final variable cname. cname=args[0];
I'm not really sure I understand the functional difference between a static and final variable/field. Oracle defines Class Variable as:
Class Variables (Static Fields) A class variable is any field declared with the static modifier; this tells the compiler that there is exactly one copy of this variable in existence, regardless of how many times the class has been instantiated. A field defining the number of gears for a particular kind of bicycle could be marked as static since conceptually the same number of gears will apply to all instances. The code static int numGears = 6; would create such a static field. Additionally, the keyword final could be added to indicate that the number of gears will never change.
If static will have the same value regardless of how many times it's used, then why use final (or vice versa)?
I have a little application that I made, it requires that I save data to a file in data/coins.cdp. When I run the application with java myProg in the terminal everything is correct, when I create the executable jar and run java -jar myJar.jar or ./myjar.jar everything also works. Even if I copy the jar to a different location, and run it through the terminal, it still works fine. Things get weird through when I copy the jar to a new location and double click on it, because then no folder gets created and no file is written.
My current URL is URL....The context rootpath is URL....In my current URL page, I upload a CSV file. This page has two buttons-- ok and Cancel and these buttons are what I'm having trouble with ( I will come to that part in a short while). The relevant JSP part is as follows.
<html:form action="importEmployee?method=save" method="POST" styleId="importEmployee" enctype="multipart/form-data"> ....... some headers and title bar and stuff... and then as follows. <div class="contentSection"> <table border="0" class="formTable"> <html:hidden property = "selectedSet" /> <tr>
[code]...
So, if I click on cancel in the second URLpage (URL...), I go back to the first URLpage, i.e to URL...But this part behaves differently in Firefox and in Chrome browsers.In Chrome, if I click on cancel in the second page, I can still see the uploaded file name( the hidden property in the first JSP is the file name ) in the first page. And if I click on ok, I can do the processing again as was done by clicking ok the first time on the first page.However when I run my application in a Firefox browser, if I click on cancel in the second page, the uploaded file name says 'no file selected' in the first page. Hence to import Employees again, I need to upload a new/same CSV file again.
I don't want the file to be present in the first page when I click on cancel in the second page even when I run my application in Chrome. Yes, I require the file name to be a hidden property. This is because depending on the data in the file, different kind of processings are done and some of them require to take additional inputs from user on another page and a third page does the processing. So the file name should be passed on to the form but I don't want the user to upload the file again.
However in the event the user clicks on cancel, I don't want the file name to be retained in the first page. But this isn't happening.So I have two questions. Why is the behaviour different in Chrome and in Firefox and is there a way I can correct the way it behaves in chrome?
I can understand basic concepts such as OOP, Threads, Events and GUI, I've coded a little but I've always had this bothering me:
Explaining by example:
public class X{ int x; String y; public static void main(String[] args){ x = 10; y = "hello ";
[Code] ....
Okay, i'm pretty certain that code won't work, but I just want to show you conceptually, not actually care whether the code works or not. In case I wanted to get that code to work I should have probably used a Swing application to get a KeyListener in the first place, but I guess I know that, and if this was working, what would happen theoretically is, the code would run, initialize x to 10, and y to hello, then when a key is pressed, it will update x to 11 and y to hello world, I'm pretty sure that's what happens.
In this case, I used a inner class to update it's parent's members, I've seen this done before and I can vouch for the fact that it's a legitimate way to code a class.
Now in this example:
class X{ int x; String y; public int getX(){ return x; } public String getY(){ return y; }
[Code] ....
So in this overly complicated example, i'm trying to share class X with both class Y and class Z, just that how to share the members of class X with the different classes without making a new instance of X. In the previous example, I could access the parent's members because the inner class was implicitly capable of accessing the parent's members. However in this case, If "Y" starts an instance of X, then how do I access it? because it's a side by side class not a hierarchy for me to access the parent's members.
I'm trying to share an hashmap(or any other stuff to share data) between a java class and a servlet. The hashmap has to be filled into the servlet with some data and then I have to get those data from the java class.
What is the best approach? I cannot use a DTO because I have several concurrent requests to my servlet.
I am new to java. I have recently learned JDBC connection pool in tomcat. To make code reuse I want to share the connection among all servlets without any conflict.
Here My code snippet:
public class GetConnection{ private DataSource ds; public Connection getConnection(){ try { InitialContext initialContext = new InitialContext(); Context context = (Context) initialContext.lookup("java:comp/env"); ds = (DataSource) context.lookup("connpool");
[Code] .....
Is this right way to do. Or I will get any problem due to concurrent threads.
Currently working on a simple file processing problem, namely, reorder a set of strings (called bid phrases) in terms of the score value associated to them in descending order.
i have very critical problem in my collage project i have try many code but still i cant solve this problem, i want to display image on jlabel or jpanel with respect of components size without use of drawimage method
I noticed that all my stages can be resized to zero size regardless of their contained scene, which is very ugly. How do I keep them from doing that? Is there some sort of intelligent way to bind the stage's min size to the size of the scene so that no part of the scene is cut off?
I would like to know the J2EE architectural explanation with respect to HTML5 and Adobe Flex technologies. It is just like knowing over all J2EE architectural aspects and how HTML5 and Adobe Flex technologies are used to satisfy those aspects in order act as client side components.
