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If you follow one of the modern patterns (MVC, MVVM etc) your GUI should be separated from your business logic such that you can test the latter even before the GUI is designed. So work on the business side of things first, it's much easier to add or modify the GUI than to rework your classes to match the display.
It's generally not good practice to have public variables, as such. Pass them as parameters or use setters and getters[^].
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Dear Richard,
Thanks for your reply, I'll study about the two patterns you suggested me.
For public variables, I show my problem:
I want to write data on RS232 port, wait a reply, read data arrived and elaborate them. I create a SerialPort object using RxTx libraries and I setted a Listener to it. In my main class, a method write the data on the serial port and then wait on a Condition variable. The listener have to notify to the waiting method the arrival of the data. The two methods are on completely different classes, so I thought to make the condition variable global. Unfortunately, at now the program doesn't work. What shall be the right way to do solve kind of problem?
Francesco
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Francesco Fraccaroli wrote: Unfortunately, at now the program doesn't work. What shall be the right way to do solve kind of problem? Sorry, but that information does not help us to understand what is happening. I suggest you open a new question, and show the part of your program that does not work, and explain exactly what errors you are seeing. Don't forget to add <pre> tags (use the code button above the edit window) around your code so it is readable like:
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Hie everyone, can someone help me on how i can open a pdf file using java. Thank you in advance.
MilwardKadzitaye
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This is only for a specific file ??
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I want one enter data in two table from one html form .
Ex. 1 student have multiple mobile no.
please provide me solution.
Praveen Kumar
Software Developer (Java)
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praveenxyz wrote: please provide me solution.
1. Learn java
2. Learn how to use spring
3. Put the above together to create code
4. Test the code to insure it works.
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anyone can help me here please :
Handling Biometric Fingerprint Attendance Device by using Socket (JAVA) Is that possible?! I try with Socket, BUT it does not executed with me!
Me Code is:
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;
import java.net.UnknownHostException;
public class Requester {
Socket requestSocket;
ObjectOutputStream out;
ObjectInputStream in;
String message;
Requester() {
}
void run() throws IOException {
try {
requestSocket = new Socket("192.168.0.19", 4370);
System.out.println("Connected to given host in port 4370");
in = new ObjectInputStream(requestSocket.getInputStream());
String line;
while (true) {
line = in.readLine();
if (line != null) {
System.out.println(line);
}
}
} catch (UnknownHostException unknownHost) {
System.err.println("You are trying to connect to an unknown host!");
} catch (IOException ioException) {
ioException.printStackTrace();
} catch (Exception Exception) {
Exception.printStackTrace();
} finally {
in.close();
requestSocket.close();
}
}
void sendMessage(String msg) {
try {
out.writeObject(msg);
out.flush();
System.out.println("client: " + msg);
} catch (IOException ioException) {
ioException.printStackTrace();
}
}
public static void main(String args[]) throws IOException {
Requester client = new Requester();
client.run();
}
}
f anyone could help me to communicate with the finger print device I will be grateful.
modified 4-Jun-14 3:55am.
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Please refer to point 9 of the forum guidelines above.
Software rusts. Simon Stephenson, ca 1994. So does this signature. me, 2012
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What does "it does not executed with me" mean; we cannot guess from this what is going wrong? Have you checked the documentation for the device to make sure your protocol is correct?
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sure I checked the documentation very well, and I am sure from the port number and IP address are correct! I mean BY "it does not executed with me" It can not read from the device, just connect and wait for response from the device without hope to retrieve the data I do not know where is the error in my code !!
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Maheera Jazi wrote: I do not know where is the error in my code Well you need to use your debugger to check what is happening internally. But, more importantly, you need to be sure that the device is functioning correctly, and communicating with your PC. And for that you need to contact the device manufacturer for help.
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yes, thanks for your response please.But, question please, you mean that it is possible to use Socket Object to retrieve the data from Fingerprint attendance machine?! as in my code!?
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Maheera Jazi wrote: you mean that it is possible to use Socket Object to retrieve the data from Fingerprint attendance machine?! No idea. As I keep saying, you must read the documentation for the device; we have no idea how it works.
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ok, thanks! although this is not mentioned on the device documentation! I will try all roads!
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Forget what is not mentioned and focus on what is. You cannot create an application to use this device by guesswork, you need to study the documentation and follow what is says. If the documentation is not clear then go back to the manufacturers and ask for help.
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Hi everyone,
I have 1 question here?
Is there any way to call public method of a child thread from its parent class
from where it is created
eg.
public class ChildThread implements Runnable{
public ChildThread(){
}
public void run(){
}
public void doMethod(){
}
}
Now I'm creating multiple ChildThread in AnotherClass
public class Parent {
Thread t;
//variables
public Parent(){
//initialization
}
//statements
private someParentMethod{
//for some event1
t=new Thread(new ChildThread(),"name1");
t.start();
}
private doSomething(){
//some event1 for name1
//want to call doMethod() of ClildThread name1
}
}
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Short answer: YES.
long answer:
I would recommend to use childThread direct and a null-check before using the member variable t:
public class ChildThread extends Thread{
public ChildThread(String name){
super(name);
}
public void run(){
}
public void doMethod(){
}
}
public class Parent {
ChildThread t;
public Parent(){
}
private someParentMethod{
t=new ChildThread("name1");
t.start();
}
private doSomething(){
if(t != null){
t.doMethod();
}
}
}
regards Torsten
I never finish anyth...
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krishna_m wrote: Is there any way to call public method of a child thread from its parent class
Yes but I am guessing that you really do not want to do that.
Typically different threads do not communicate except very explicitly. Note that I said "thread" not class. If you want a thread to communicate with another thread then you first figure out what the best way to do that is and THEN you figure out which classes will do it (and how.)
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hi everyone,
I need java program for converting pdf file into excel file. please help me.
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1. find a library that reads pdfs.
2. Find a library that writes excel files.
3. Spend a LOT of time figuring out what to do with all the differences between pdfs and excel file.
4. Write code that implement 3 and uses 1 and 2.
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