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You define a
discrete random variable X that assumes values represent your awards and losses when you play the
game. For simplicity, assume that the awards are positive and the losses are negative. Each award
or a loss is associated with a probability. You run the game many times, at each time you randomly
select a value for the random variable and multiply the result by its probability. After m runs of the
programs, your program must give a recommendation whether you play the game or not.
Remember if the expected value of the random variable is negative, it is a losing game; wining
otherwise.
You program should allow the user to input the values of the random variable and their associated
probability and the number of runs m. After doing the experiment, the program prints the
recommendation.
please help i cant do it!!!!!
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Member 11384820 wrote: please help i cant do it!
Can't do what? If you mean you can't do anything then I suggest you go to The Java Tutorials[^] and work through the tutorials. If you mean something specific (see How to ask a question[^]) then please provide the details.
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We have a time values in CSV sheet, needs to generate a Graph for time values on X-axis and have to set a proper scale on Y-axis,
Graph should be in xlsx format, so we are converting csv to xlsx,but because of string or time/date data type it is unable to convert
complete data to xlsx which leads graph is not generating and also we are unable to fix a intervals on Y-axis.
Environment Using : Eclipse
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Does this have anything to do with Java?
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Hi everyone
i created exe file of a java desktop application which use a sqlite database when i install the project an i run it i give the error of attempt to write a redinly database and sometimes access in denied error
how to fix it?
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Member 11110116 wrote: how to fix it?
With that level of detail it is anyone's guess. Please show the failing code and provide exact details of any error messages.
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i just want to insert some data there is no more and difficult code
connectivity code:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import javax.swing.JOptionPane;
public class Sqliteconn {
public static Statement sqliteStmt()
{
try{
Class.forName("org.sqlite.JDBC");
Connection conn = DriverManager.getConnection("jdbc:sqlite:B12MSqlite.sqlite");
Statement stmt=conn.createStatement();
return stmt;
}
catch(Exception e)
{
JOptionPane.showMessageDialog(null, e);
return null;
}
}
}
and insert Button Code:
String query="Insert into Employee values('"+txtID.getText()+"','"+txtName.getText()+"','"+txtFName.getText()+"','"+txtEmail.getText()+"')";
try{
Sqliteconn.sqliteStmt().execute(query);
}
catch(Exception e)
{
JOptionPane.showMessageDialog(null, e);
}
Erorr messages
java.sql.sqlexception attempt to write a readonly database
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A couple of things first in the following code:
String query="Insert into Employee values('"+txtID.getText()+"','"+txtName.getText()+"','"+txtFName.getText()+"','"+txtEmail.getText()+"')";
try{
Sqliteconn.sqliteStmt().execute(query);
}
Do not use string concatenation in this way to create SQL statements, it leaves your code vulnerable to SQL injection, and the corruption or destruction of your database. Use properly constructed parameterised statements.
Also you should split the execute statement into two parts for easier debugging.
As to your error, you need to establish why the database is not writable by your program. Do you have permission to write in the folder where the database is stored?
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thanks for your reply
my database is stored in same folder with project and how to allow the permission of writing?
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Check permissions and access rights of the folder and the database and see why your application cannot write to the file.
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It can be folder read & write permission issue where you are trying to install application
rahul
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Obviously when it is a "folder read & write permission issue" then you fix it by fixing that issue.
And that is not a java issue.
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bro it works properly when i open and run it in netbeans but when i create its setup and install and run it , it give the error.
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It is no good reposting this information repeatedly, until you have found out why you are prevented from writing to this database. Look at the directories where the files are installed and check the permissions on them, and do the same for all associated files.
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Thank you bro u solved the problem tnx again
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I'm quite new to Java, and recently I've been experimenting with the GridbagLayout manager...
Specifically I'm using it to define panels for a Choose-your-own-adventure game...
As, time passed I noticed that I had created an overwhelming long piece of code...
The number of panes that were essentially identical aside from the text I had put into each of their respective JTextAreas, coupled with the inherent length of the calibrating each Jpanel's GridbagLayout has caused my code to balloon up to a ridiculous degree...
...
So, my question is this:
Is there a method of reducing the immense length of such a piece of code...
Thanks in advance...
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Member 12229369 wrote: Is there a method of reducing the immense length of such a piece of code...
Yes, there are many methods. However, without some more specific details it is anyone's guess what they should be.
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Hi, I want to combine the two variables Variable1 and Variable2, but I couldn't combine them.
This is a separate class java file:
public class AnswerList {
private int mQuestion;
private int mAnswer;
private int mChoice1;
private int mChoice2;
private int mChoice3;
private int mChoice4;
public AnswerList(int question, int choice1, int choice2, int choice3, int choice4, int answer){
mQuestion = question;
mAnswer = answer;
mChoice1 = choice1;
mChoice2 = choice2;
mChoice3 = choice3;
mChoice4 = choice4;
}
I have to declared the two variables separately because I want to combine the two only if certain conditions are met. The issue I have is I can't get the combining to work.
private AnswerList[] Variable1 = new AnswerList[] {
new AnswerList(R.string.question1, R.string.answerone1,
R.string.answerone2, R.string.answerone3,
R.string.answerone4, 4),
new AnswerList(R.string.question2, R.string.answertwo1,
R.string.answertwo2, R.string.answertwo3, R.string.answertwo4, 2)};
private AnswerList[] Variable2 = new AnswerList[]{
new AnswerList(R.string.question5, R.string.answerfive1,
R.string.answerfive2, R.string.answerfive3,
R.string.answerfive4, 1)
};
I tried to used the following codes to combine them, but none of them worked. What am I doing wrong? Thanks!
Note: I am a Java/Android beginner.
Arrays combined = ArrayUtils.addAll(Variable1,Variable2);
Collections.addAll(Variable1,Variable2);
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As Richard advised - use collection instead of fixed-length arrays: I think this will be more useful for the beginner:
private ArrayList<AnswerList> Variable1 = new ArrayList<AnswerList>();
private ArrayList<AnswerList> Variable2 = new ArrayList<AnswerList>();
Variable1.add(new AnswerList(R.string.question1, R.string.answerone1,
R..string.answerone2, R.string.answerone3,
R.string.answerone4, 4));
Variable1.add(new AnswerList(R.string.question2, R.string.answertwo1,
R.string.answertwo2, R.string.answertwo3,
R.string.answertwo4, 2));
Variable12.add(new AnswerList(R.string.question5, R.string.answerfive1,
R.string.answerfive2, R.string.answerfive3,
R.string.answerfive4, 1));
Once your collections are populated and certain condition is met, you can call someting like
ArrayList<AnswerList> collatedList = collateAnswers(Variable1, Variable2);
Function collateAnswers() is deliberatly implemented in "step-by-step" way - for the beginner's benifits.
public ArrayList<AnswerList> collateAnswers(ArrayList<AnswerList> lst1, ArrayList<AnswerList> lst2){
ArrayList<AnswerList> lst = new ArrayList<AnswerList>();
for(AnswerList x : lst1){
lst.add(x);
}
for(AnswerList x : lst2){
lst.add(x);
}
return lst;
}
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1)One String given(Ex-"2a3b4c...").How to print aabbbcccc.....like this.
2)How to check a given index in a String is number or char.
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What is best to use. Mostly I use METHOD POST for this action (Add, Update, Delete)
In User Module.
1. Create Servlet for each Action (Login, Create, Update, Delete)
OR
2. In JSP for each FORM create a input hidden which contains the process (Login, Create, Update, Delete) and Create one Servlet that read this hidden input and process specific action.
- Be who you are and say what you feel because those who mind don't matter and those who matter don't mind.
- Most of the problem in your life are due to two reasons: you act without thinking, or think without acting.
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I am writing a (TCP v4) server that accepts connections for all available network interfaces.
Server gets a value frim thouthends of clients and searches/sorts data based on that value. Then, returns an array of string values back to clients.
What is the best choice for this task: ExecutorService vs ForkJoinPool vs standard threads?
Here is the code for standard threads, is there anything to improve?
while (!Thread.currentThread().isInterrupted()) {
try (Socket socket = new ServerSocket(init()).accept()) {
new Thread(new Runnable() {
@Override
public void run() {
while (true) {
try (BufferedReader fromClient = new BufferedReader(new InputStreamReader(socket.getInputStream(), StandardCharsets.US_ASCII));
DataOutputStream outToClient = new DataOutputStream(socket.getOutputStream()); ) {
outToClient.write(autocomplete(fromClient.readLine()).getBytes("US-ASCII"));
} catch (IOException e) { Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, e.getMessage()); }
}
}
}).start();
} catch (IOException ex) { Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex.getMessage()); }
}
Code for ExecutorService:
final ExecutorService service = Executors.newCachedThreadPool();
while(!Thread.currentThread().isInterrupted()) {
service.submit(new Runnable() {
public void run() {
try (Socket socket = new ServerSocket(init()).accept();
BufferedReader fromClient = new BufferedReader(new InputStreamReader(socket.getInputStream(), StandardCharsets.US_ASCII));
DataOutputStream outToClient = new DataOutputStream(socket.getOutputStream());) {
outToClient.write(autocomplete(fromClient.readLine()).getBytes("US-ASCII"));
} catch (IOException e) {
service.shutdown();
Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, e.getMessage());
}
}
});
}
Or should I use ForkJoinPool...?
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