Readers And Writer In Concurrency
May 23, 2014I put the code on pastebin.com because it is relatively long. How to improve this code that does not occur starvation and was ucziwy terms of writers and readers.
[URL] .....
ADVERTISEMENT
EJB / EE :: Session Beans Concurrency
Jan 13, 2015I'm trying to understand the concurrent model of each EJB session bean types.
The singleton is well documented and seems clear to me... Only one instance and many threads using it but each method by default is synchronized because @Lock is defaulted to WRITE. We can let multiple threads use on method with @Lock(READ).
The stateless beans are in a pool I think I read somewhere that the container will ensure only one thread is using one instance at a time but this instances are recycled/reused so many threads can use the same instance but one at a time.
Is this correct ? or is it possible that multi-threading occur in one instance of SLSB ?If in the client I obtain a single reference of a SLSB and share this "instance reference" in multiple threads is it true that all the threads could use different instances on the server side ?
The stateful instance I obtain in the client is linked to one server instance and any method call will target the same instace. If many threads are using the same reference, all method calls will be synchronized and waiting for a certain amount of time that can be defined in @AccessTimeout and if the timeout is reach will end with a ConcurrentAccessException.
Can we use @Lock(READ) and let many thread use the same method like in a singleton ?
Writing To Database (concurrency)
Feb 11, 2014Recently I discovered power of Java, I'm coming from Perl, Python world so I'm at very beginning. I have firm understanding of OOP and I'm ready for new challenges. I have question regarding writing to database performance and theory.
Basically as my personal project I'm trying to write some small program or addon which will enable me to write concurrently to database. Let's say that I have some software and that has FIFO output to database in single stream, but since the output interface is not fast enough congestion can occur if the input to the system is high.
I would like to extend that software with addon which will take that one output stream and create 2,3,4 concurrent input streams towards database. API from that software is provided so I can redirect output to third-party extensions and apps.
Java IO File Reader / Writer
Feb 2, 2015I've been working on a saving system for a game I'm working on using java IO writer and reader. When I tried exporting it (as a executable jar) to test I couldn't get it to work, when it worked before. If I had to guess it's the file location not being able to find the file. Which it just looks like :
FileReader end = new FileReader("Saves.txt");
I don't exactly know how to set it up to read the file. I'd tried giving it a look up but I don't know how to exactly word my problem.
Print Writer And Reading Files
Apr 10, 2015how to use a Scanner to read data from a file. Is it possible to also average a set of numbers at the same time its being read?
View Replies View RelatedWrite To TXT File Using Buffered Writer
Sep 22, 2014Trying to write to a txt file using buffered writer - however I'm getting some issues.
BufferedWriter says 'The resource type BufferedWriter does not implement java.lang.AutoCloseable'
br says 'The type BufferedWriter is not visible'
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
public class FileWriter {
public static void main(String[]args){
[Code] .....
Buffered Writer / FileWriter Not Writing To File In Netbeans?
Apr 2, 2014I am using netbeans to create a hotel booking system, just tessting out code to get the booking information input to a file when the next button is clicked.
File file = new File("file.txt");
try (BufferedWriter br = new BufferedWriter(new FileWriter(file))) {
br.write("################################");
br.newLine();
br.write(" Booking Information");
br.newLine();
br.newLine();;
br.write("First Name: " + TxtName.getText());
} catch (IOException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
Nothing is getting wrote to the file though. Does that code seem right?
I/O / Streams :: Unable To Create A Print Writer To Write To File
Apr 25, 2014I am completing a USACO online problem and am trying to create a print writer to write to my file(ride.out). I did this:
PrintWriter out = new PrintWriter(new BufferedReader(new FileWriter("ride.out")));
However, a load of undefined constructor errors come up for PrintWriter(BufferedWriter) and BufferedWriter(FileWriter). I have imported java.io.* so I don't know what the issue is. This has worked before.
edit: bufferedreader? i give up(not literally)
Print Writer Won't Fill Output File / Blank Every Time
Apr 10, 2014I am trying to write to an output file that the user names. I have flushed and closed the printwriter, so now I am at a loss. The console output works fine with the formatting, and the file is created, but I cannot get the file to populate. I have the following:
public static void main(String[] args) {
try
{
Scanner kb = new Scanner(System.in);
System.out.print("Input file: ");
String inputFileName = kb.next();
System.out.print("Output file: ");
String outputFileName = kb.next();
// Construct the Scanner and PrintWriter objects for reading and writing
File inputFile = new File(inputFileName);
Scanner in = new Scanner(inputFile);
PrintWriter out = new PrintWriter(outputFileName);
[code]....