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Apache Jena SPARQL query will not abort

I'm having a problem in my Java application where Apache Jena will never stop a SPARQL query until it's finished, even if I explicitly tell it to stop. Here's the code that gets called to run a query:
try {
Model union = null;
union = ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM_RULE_INF);
if (ontologies != null)
for (OntModel om : ontologies)
union = ModelFactory.createUnion(union, om);
Reasoner reasoner = ReasonerRegistry.getOWLReasoner();
reasoner = reasoner.bindSchema(union);
InfModel infmodel = ModelFactory.createInfModel(reasoner, triples);
query_running = true;
Query query = QueryFactory.create(query_string);
query_execution = QueryExecutionFactory.create(query, infmodel);
ResultSet rs = query_execution.execSelect();
for ( ; rs.hasNext(); ) {
// do stuff with results
}
} catch (Exception e) {}
finally {
stopQuery();
}
stopQuery() gets called at the end, but the method is also called when the user hits a "cancel" button. Here's what that method looks like:
public void stopQuery() {
try {
if (query_execution != null) {
//query_execution.close();
query_execution.abort();
query_execution = null;
System.out.println("STOPPED");
}
} catch (Exception e) { e.printStackTrace(); }
query_running = false;
}
When the cancel button is hit while a query is running (10+ minutes on a relatively small dataset...?), the method gets called, but the query continues to run in the background. I know it's still running because I can see the application in task manager taking up 30%+ CPU until the query presumably completes. I've tried .abort(), .close(), and both at the same time, but I cannot figure out how to stop the query mid-execution. I've even tried wrapping the query code in a separate thread, but that doesn't work either. It makes sense that threading wouldn't solve the problem because the thread needs to see the interrupt request, but the code is freezing on a particular line. The code seems to freeze on rs.hasNext(), but not the first check. It will run quickly with the first x results of the ResultSet (which are likely explicit statements it finds easily), but then it will seem to freeze for a long while after that, likely searching for implicit results with the reasoner. How can I force the query to stop? I don't want to use a timeout -- I want the user to have the option to stop the query or let it play out. This problem is not specific to any one query or dataset.
Thanks.

How to get information about "operation finished with success" after native query?

I am creating web-app which will be used to database managament. Now i am trying to implement "sql interpreter" and after input some incorrect queries i need to print sql errors. Here is my code:
public String executeSQL(String[] split){
SessionFactory hibernateFactory = someService.getHibernateFactory();
Session session = hibernateFactory.openSession();
String feedback= null;
for (int i = 0; i < split.length; i++) {
try{
String query = split[i];
session.doWork(connection -> connection.prepareStatement(query).execute());
feedback= "Success";
}
catch(Exception e){
feedback= ((SQLGrammarException) e).getSQLException().getMessage();
}
}
session.close();
return feedback;
}
My question:
Is there any way to get "positive message"? I mean: if i will do for example: 'insert into table' i want message:
"1 rows affected"
You know what i mean, i want that information from sql compiler:

You can use my open source program plsql_lexer to generate information about the success of an operation. The program imitates the feedback messages produced by SQL*Plus. The program handles all documented (and some undocumented) command types. The downside is that it must be installed on the database and requires a separate call to the database.
For example, after installing the program (which is mostly just download and run "#install"), create a simple function like this:
create or replace function get_success_message
(
p_statement clob,
p_number_of_rows number
) return varchar2 is
v_success_message varchar2(4000);
v_ignore varchar2(4000);
begin
--Get the feedback message.
statement_feedback.get_feedback_message(
p_tokens => plsql_lexer.lex(p_statement),
p_rowcount => p_number_of_rows,
p_success_message => v_success_message,
p_compile_warning_message => v_ignore
);
return v_success_message;
end;
/
Now you can generate feedback messages by calling the function, like this:
select
get_success_message('insert into test1 values(1)', 1) insert_1,
get_success_message('insert into test1 values(1)', 0) insert_0,
get_success_message('delete from test1', 50) delete_50
from dual;
INSERT_1 INSERT_0 DELETE_50
-------------- --------------- ----------------
1 row created. 0 rows created. 50 rows deleted.
The program was built to create database-centric, private SQL Fiddles, and may help with other tasks related to running arbitrary database commands.

How to fix "GetStatus Write RFID_API_UNKNOWN_ERROR data(x)- Field can Only Take Word values" Android RFID 8500 Zebra

I am trying to develop and application to read and write to RF tags. Reading is flawless, but I'm having issues with writing. Specifically the error "GetStatus Write RFID_API_UNKNOWN_ERROR data(x)- Field can Only Take Word values"
I have tried reverse-engineering the Zebra RFID API Mobile by obtaining the .apk and decoding it, but the code is obfuscated and I am not able to decypher why that application's Write works and mine doesn't.
I see the error in the https://www.ptsmobile.com/rfd8500/rfd8500-rfid-developer-guide.pdf at page 185, but I have no idea what's causing it.
I've tried forcefully changing the writeData to Hex, before I realized that the API does that on its own, I've tried changing the Length of the writeData as well, but it just gets a null value. I'm so lost.
public boolean WriteTag(String sourceEPC, long Password, MEMORY_BANK memory_bank, String targetData, int offset) {
Log.d(TAG, "WriteTag " + targetData);
try {
TagData tagData = null;
String tagId = sourceEPC;
TagAccess tagAccess = new TagAccess();
tagAccess.getClass();
TagAccess.WriteAccessParams writeAccessParams = tagAccess.new WriteAccessParams();
String writeData = targetData; //write data in string
writeAccessParams.setAccessPassword(Password);
writeAccessParams.setMemoryBank(MEMORY_BANK.MEMORY_BANK_USER);
writeAccessParams.setOffset(offset); // start writing from word offset 0
writeAccessParams.setWriteData(writeData);
// set retries in case of partial write happens
writeAccessParams.setWriteRetries(3);
// data length in words
System.out.println("length: " + writeData.length()/4);
System.out.println("length: " + writeData.length());
writeAccessParams.setWriteDataLength(writeData.length()/4);
// 5th parameter bPrefilter flag is true which means API will apply pre filter internally
// 6th parameter should be true in case of changing EPC ID it self i.e. source and target both is EPC
boolean useTIDfilter = memory_bank == MEMORY_BANK.MEMORY_BANK_EPC;
reader.Actions.TagAccess.writeWait(tagId, writeAccessParams, null, tagData, true, useTIDfilter);
} catch (InvalidUsageException e) {
System.out.println("INVALID USAGE EXCEPTION: " + e.getInfo());
e.printStackTrace();
return false;
} catch (OperationFailureException e) {
//System.out.println("OPERATION FAILURE EXCEPTION");
System.out.println("OPERATION FAILURE EXCEPTION: " + e.getResults().toString());
e.printStackTrace();
return false;
}
return true;
}
With
Password being 00
sourceEPC being the Tag ID obtained after reading
Memory Bank being MEMORY_BANK.MEMORY_BANK_USER
target data being "8426017056458"
offset being 0
It just keeps giving me "GetStatus Write RFID_API_UNKNOWN_ERROR data(x)- Field can Only Take Word values" and I have no idea why this is the case, nor I know what a "Word value" is, and i've searched for it. This is all under the "OperationFailureException", as well. Any help would be appreciated, as there's almost no resources online for this kind of thing.

Even this question is a bit older, I had the same problem so as far as I know this should be the answer.
Your target data "8426017056458" length is 13 and at writeAccessParams.setWriteDataLength(writeData.length()/4)
you are devide it with four. Now if you are trying to write the target data it is longer than the determined WriteDataLength. And this throws the Error.
One 'word' is 4 Hex => 16 Bits long. So your Data have to be filled up first and convert it to Hex.

else statement still runs even when else if condtions pass

I'm having issues getting my if else statement to work correctly, here I have a login in form that uses values from a database. The statement for the Employee role works fine but even if the else if statement passes the else statement still runs.
If it helps the dialog box appears twice if the Customer statement passes and three time if the else runs by itself. I apologize if my code format is off I'm new at posting code here.
private void jBtnLoginActionPerformed(java.awt.event.ActionEvent evt) {
// action performed when the login button is pressed
// variables that will contain the row entries to the login data base (user name)
String userNameDb = "";
roleDb = rs.getString("role");
//database connection code
try
{
Class.forName("org.sqlite.JDBC");
con = DriverManager.getConnection("//database directory");
st=con.createStatement();
//selects entries from the userName password and role row from the user table
rs=st.executeQuery("Select userName, role From tblUser ;");
//loops through the table entires
while(rs.next())
{
//assigns database entry to variables
userNameDb = rs.getString("userName");
roleDb = rs.getString("role");
if (jTxtUserName.getText().equals(userNameDb) && roleDb.equals("Customer"))
{
//switch forms
break;
}
//if the users input and role match the data base for an customer send them to the selection form
else if (jTxtUserName.getText().equals(userNameDb) && roleDb.equals("Customer"))
{
//switch forms
break;
}
else
{
JOptionPane.showMessageDialog(null, "Login failed");
}
}
}
catch(Exception ex)
{
System.out.println("" + ex);
}
}
}

The problem is that your while loop is coded wrong as your "Login failed" JOptionPane else block shouldn't be within the while loop. Instead declare a boolean value before the loop, set it to false, check if the username/password are found within the that loop, and if so, set the boolean to true. Then after the loop check the boolean value, and if false, show the error message.
To see why, use a debugger to run through the code to see why it's behaving the way it's behaving. More importantly, learn the "rubber duck" debugging technique where you walk through your code mentally or on paper, telling the duck what each line of code should be doing.
To illustrate, your code is behaving something like the code below where a boolean array is mimicking your password username check. Of course, you'd be using a while loop, not a for loop, but this was used here to make the example simpler:
private someActionPerformedMethod() {
// boolean representing when the username/password test is OK
boolean[] loopItems = { false, false, false, true, false };
for (boolean loopItem : loopItems) {
if (loopItem) {
break;
} else {
JOptionPane.showMessageDialog(null, "Login failed");
}
}
}
Assume that the password/username only matches on the 4th try (forth item is true), then for each failed check, the JOptionPane will show a failed login. What you want instead is something like:
private someActionPerformedMethod() {
// boolean representing when the username/password test is OK
boolean[] loopItems = { false, false, false, true, false };
boolean userFound = false;
// you'll of course be using a while loop here
for (boolean loopItem : loopItems) {
if (loopItem) {
userFound = true;
// do something with user data
break;
}
}
if (!userFound) {
JOptionPane.showMessageDialog(null, "Login failed");
}
}

Max 20 Friends Information on Twitter4J

Like you see in this code, I want to get all the information about friends in twitter, people I follow.
But doing this :
PagableResponseList<User> users = twitter.getFriendsList(USER_ID, CURSOR);
... only gives me the first 20 recent friends... What can I do?
Complete code about it :
PagableResponseList<User> users = twitter.getFriendsList(USER_ID, CURSOR);
User user = null;
max = users.size();
System.out.println("Following: "+max);
for (int i = 0 ; i < users.size() ; i++){
user = users.get(i);
System.out.print("\nID: "+user.getId()+" / User: "+user.getName()+" /");
System.out.print("\nFollowers: "+user.getFollowersCount()+"\n");
tid.add(Long.parseLong(String.valueOf(user.getId())));
tusername.add(user.getName());
tfollowers.add(Long.parseLong(String.valueOf(user.getFollowersCount())));
tname.add(user.getScreenName());
}
Thanks..

you can try this code to get the list of people you follow.
long cursor = -1;
PagableResponseList<User> users;
while ((cursor = followers.getNextCursor()) != 0);
{
users = twitter.getFriendsList(userId, cursor);
}

I've taken a peek at the documentation at Twitter4J and Twitter themselves and it's all about that cursor.
To prevent you're getting loaded with a whole bunch of friends at once, Twitter only returns the first 20 results. It doesn't return just the first 20 results, but it also returns a cursor. That cursor is just a random number that's managed by Twitter. When you make a call again and pass this cursor, the next 20 entries (friends) will be returned, again with a cursor that's different now. You can repeat this until the cursor returned is zero. That means there are no more entries available.
In case you want to know more, check these two links: Twitter DEV and Twitter4J documentation.
Concerning your Java, you just need to find a way to get the current cursor, and pass that cursor to your method again, making the app load the next 20 entries. According to this piece of information, that should do the trick.
List<User> allUsers = new ArrayList<User>();
PagableResponseList<User> users;
long cursor = -1;
while (cursor != 0) {
users = twitter.getFriendsList(USER_ID, cursor);
cursor = users.getNextCursor();
allUsers.add(users);
}

You should be able to request up to 200 results at a time:
final PagableResponseList<User> users = twitter.getFriendsList(USER_ID, cursor, 200);
cursor = users.getNextCursor();
If you need to start from where you left off between invocations of your program then you need to store the value of cursor somewhere.

Improvements to Sander's answer!
You can set a count value to the getFriendsList method as in Jonathan's Answer. The maximum value allowed for count is 200. The loop construct will help to collect more than 200 friends now. 200 friends per page or per iteration!
Yet, there are rate limits for any request you make. The getFriendsList method will use this api endpoint: GET friends/list which has a rate limit of 15 hits per 15 minutes. Each hit can fetch a maximum of 200 friends which equates to a total of 3000 friends (15 x 200 = 3000) per 15 minutes. So, there will be no problem if you have only 3000 friends. If you have more than 3000 friends, an exception will be thrown. You can use the RateLimitStatus class to avoid that exception. The following code is an example implementation to achieve this.
Method 1: fetchFriends(long userId)
public List<User> fetchFriends(long userId) {
List<User> friends = new ArrayList<User>();
PagableResponseList<User> page;
long cursor = -1;
try {
while (cursor != 0) {
page = twitter.getFriendsList(userId, cursor, 200);
friends.addAll(page);
System.out.println("Total number of friends fetched so far: " + friends.size());
cursor = page.getNextCursor();
this.handleRateLimit(page.getRateLimitStatus());
}
} catch (TwitterException e) {
e.printStackTrace();
}
return friends;
}
Method 2: handleRateLimit(RateLimitStatus rls)
private void handleRateLimit(RateLimitStatus rls) {
int remaining = rls.getRemaining();
System.out.println("Rate Limit Remaining: " + remaining);
if (remaining == 0) {
int resetTime = rls.getSecondsUntilReset() + 5;
int sleep = (resetTime * 1000);
try {
if(sleep > 0) {
System.out.println("Rate Limit Exceeded. Sleep for " + (sleep / 1000) + " seconds..");
Thread.sleep(sleep);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
By doing so, your program will sleep for some time period based on the rate limiting threshold. It will continue to run from where it left after the sleep. This way we can avoid our program stopping in the midway of collecting friends counting more than 3000.

I have the solution to my post... thanks to Sander, give me some ideas...
The thing was change the for to while ((CURSOR = ids.getNextCursor()) != 0);.
And... user = twitter.showUser(id);
Playing with showUser makes it possible to get, with a slowly time, all the info about all my friends...
That's all. Don't use user.get(i);