Develop Reference

How to know which row was selected from another Frame?

In the first Jframe I have a JTable filled from database and i need to pass data of the selected jTable to another frame.
So I need to know from another JInternalFrame which row was selected in the First Jframe
public void showTableData() {
try {
Class.forName(driverName);
Connection con = DriverManager.getConnection(url, userName, password);
String sql = "SELECT t.name, t.exam, l.coursename\n"
+ "FROM exam AS t\n"
+ "INNER JOIN Course as l ON (t.LendaID=l.LendaID)";
PreparedStatement ps = con.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
int i = 0;
Jtable1.setModel(DbUtils.resultSetToTableModel(rs));
} catch (Exception ex) {
ex.printStackTrace();
JOptionPane.showMessageDialog(null, ex.getMessage(), "Error",
JOptionPane.ERROR_MESSAGE);
}
}
This is the table I've in the first Jframe

Regardless the number of your components, as a simple solution, you can create a CourseEventDispatcher class to be central point to dispatch course events across the application.
public class CourseEventDispatcher {
private List<CourseEventSubscriber> subscribers;
// ...
public void dispatchEvent(CourseEvent event) {
for(CourseEventSubscriber: subscribers) {
if( event.getSource() != subscriber ) {
subscriber.onCourseEvent(event);
}
}
}
}
And for each relevant view, there is a controller which is a CourseEventSubscriber:
public class SomeFrameController implements CourseEventSubscriber {
private CourseEventDispatcher courseEventDispatcher;
public SomeFrameController(CourseEventDispatcher courseEventDispather) {
this.courseEventDispatcher = courseEventDispatcher;
}
public void addSelectionListener() {
// ...
table.getSelectionModel().addListSelectionListener(
new ListSelectionListener() {
public void valueChanged(ListSelectionEvent event) {
doYourOwnStuff();
// then dispatch the event
courseEventDispatcher.dispatch(new CourseEvent(this, event));
}
}
);
}
// from some other view
public void onCourseEvent(CourseEvent event) {
// process the event
// e.g. event.getEvent()
}
}
And CourseEvent is a simple class of
public class CourseEvent {
private CourseEventSubscriber source;
private EventObject event;
public CourseEvent(CourseEventSubscriber source, EventObject event) {
this.source = source;
this.event = event;
}
// getters
}
You can add(register) your controllers after you created a dispatcher.
Hope this gives you another perspective.

How to use a database for merge after download?

I'm using Ormlite, for my android app, to store my data. I want to download a database from a site and after this, the program checks if a database exists. If a database exists, then the new database and the old database should merge.
Here comes my problem. In Ormlite you create a Dao to interact with the tables of a database and I wanted to know, how I can interact with the new database after the download?
For example:
Database A from the app has the items:
Cheese, Eggs, Milk, Chicken
Database B from the download has the items:
Cheese, Eggs, Milk, Flour, Bread
At the end I want:
Cheese, Eggs, Milk, Flour, Bread, Chicken and only one database left.
And to clarify: Yes, it exists questions "How to merge databases".
For example:
Android update - merge database contents?
But that is not my problem. I want to know, how to interact with the new database with Ormlite. Which way exists, that I can get access to the new database?
Edit:
I tried to download the database and guarantee that the version is always higher than the old database version. Therefore, at least that what I thought, it would go in OnUpgrade method and there I could merge the database. But i just replaced the old database.
I also tried to make a second OrmDBHelper with another name, so after the download I could use the methods there. But no errors or anything whatsoever.
Here is the database helper from the existing database and the second one is the same, except the name.
public class OrmDbHelper extends OrmLiteSqliteOpenHelper {
public static final String LOG = OrmDbHelper.class.getName();
public static final String DB_NAME = "bestand.db";
public static final int DB_VERSION = 1;
public OrmDbHelper(Context context) {
super(context, Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath()
+ File.separator + DB_NAME, null, DB_VERSION);
}
#Override
public void onCreate(SQLiteDatabase database, ConnectionSource connectionSource) {
try {
TableUtils.createTableIfNotExists(connectionSource, ScanItem.class);
TableUtils.createTableIfNotExists(connectionSource, BestandItem.class);
TableUtils.createTableIfNotExists(connectionSource, SettingsItem.class);
} catch (SQLException ex) {
Log.e(LOG, "Error Creating table", ex);
}
}
#Override
public void onUpgrade(SQLiteDatabase database, ConnectionSource connectionSource, int oldVersion, int newVersion) {
try {
TableUtils.dropTable(connectionSource, ScanItem.class, true);
TableUtils.dropTable(connectionSource, BestandItem.class, true);
TableUtils.dropTable(connectionSource, SettingsItem.class, true);
TableUtils.createTable(connectionSource, ScanItem.class);
TableUtils.createTable(connectionSource, BestandItem.class);
TableUtils.createTable(connectionSource, SettingsItem.class);
} catch (SQLException ex) {
Log.e(LOG, "Error Updating table", ex);
}
}
public Dao<ScanItem, Integer> createScanItemDAO() {
try {
return DaoManager.createDao(connectionSource, ScanItem.class);
} catch (SQLException ex) {
Log.e(LOG, "Error Creating DAO for Todo class", ex);
}
return null;
}
public Dao<BestandItem, Integer> createBestandItemDAO() {
try {
return DaoManager.createDao(connectionSource, BestandItem.class);
} catch (SQLException ex) {
Log.e(LOG, "Error Creating DAO for Todo class", ex);
}
return null;
}
public Dao<SettingsItem, Integer> createSettingItemDAO() {
try {
return DaoManager.createDao(connectionSource, SettingsItem.class);
} catch (SQLException ex) {
Log.e(LOG, "Error Creating DAO for Todo class", ex);
}
return null;
}
}
And here is how I tried to get access to the second database:
The access to the first database works, but to the second one doesnt. I even checked if the download of the second database works, which it does.
public class OrmDataHelper {
private Dao<ScanItem, Integer> scanItemDAO;
private Dao<BestandItem, Integer> bestandItemDAO;
private Dao<SettingsItem, Integer> settingsItemsDAO;
public OrmDataHelper(Context context) {
OrmDbHelper ormDbHelper = new OrmDbHelper(context);
scanItemDAO = ormDbHelper.createScanItemDAO();
bestandItemDAO = ormDbHelper.createBestandItemDAO();
settingsItemsDAO = ormDbHelper.createSettingItemDAO();
}
public ArrayList<ScanItem> getAllScanItem() {
ArrayList<ScanItem> temp = null;
try {
temp = new ArrayList<>(scanItemDAO.queryForAll());
} catch (SQLException ex) {
ex.getMessage();
}
return temp;
}

Showing output in web browser

I have a spring boot application. These are the classes:
RunBatchFile.java
public class RunBatchFile {
private Boolean isSuccessful;
private String content;
public void RunningBatchCommand() {
String filePath = "C:/Users/attsuap1/Desktop/test.bat";
try {
Process p = Runtime.getRuntime().exec(filePath);
int exitVal = p.waitFor();
if (exitVal == 0)
{
isSuccessful = true;
}
else {
isSuccessful = false;
}
System.out.println(isSuccessful);
} catch (Exception e) {
e.printStackTrace();
}
}
public RunBatchFile(Boolean isSuccessful) {
this.isSuccessful = isSuccessful;
this.content = content;
}
public RunBatchFile(String format) {
// TODO Auto-generated constructor stub
}
public Boolean getisSuccessful() {
return isSuccessful;
}
public String getContent() {
return content;
}
}
BatchFileController
#RestController
public class BatchFileController {
private static final String template = "Sum, %s!";
private static boolean isSuccessful;
#RequestMapping("/runbatchfile")
#ResponseBody
public RunBatchFile runbatchFile(#RequestParam(value = "isSuccessful") Boolean isSuccessful) {
return new RunBatchFile(String.format(template, isSuccessful));
}
}
The runBatchFile.java class executes a batch file and will show output as either true or false depending on whether the batch file has executed its commands correctly or not. I want to display that output on a web browser therefore i have created the BatchFileController.java class.
I get the error:
Required Boolean parameter 'isSuccessful' is not present
How do i edit my codes to make this work? Which means, either {true} or {false} is shown on the web browser when i run localhost:8080/runbatchfile?

I'm not quite sure what you are doing. The issue you are having with your controller is that you have defined your method to require a boolean parameter. Given your scenario, that would not make sense, as you would not tell the endpoint the result of the script running; the endpoint tells you that. Your method return type should be boolean instead.
Generally this would be the way to go about this if it is a short running script. I tested with a simple ping command and things worked out. Pointing to an invalid IP failed.
If the script takes a lot of time, you're going to want to go async where you submit a job, and you can check back with a different method to see what the status is.
I would have a class to run your batch file:
public class RunBatchFile {
public boolean runBatch() {
String filePath = "C:/Users/attsuap1/Desktop/test.bat";
try {
Process p = Runtime.getRuntime().exec(filePath);
int exitVal = p.waitFor();
return exitVal == 0;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
}
And then in your controller:
#RequestMapping("/runbatchfile")
public boolean runbatchFile() {
RunBatchFile rbf = new RunBatchFile();
return rbf.runBatch();
}
If you want to wrap your results so your response isn't just a true/false string. Note that the return type of the method has changed to a simple POJO:
Class
public class RunBatchFile {
public ResultWrapper runBatch() {
String filePath = "C:/Users/attsuap1/Desktop/test.bat";
try {
Process p = Runtime.getRuntime().exec(filePath);
int exitVal = p.waitFor();
return new ResultWrapper(exitVal == 0);
} catch (Exception e) {
e.printStackTrace();
return new ResultWrapper(false);
}
}
}
Wrapper Class
public class ResultWrapper {
private boolean result;
public ResultWrapper(boolean result) {
this.result = result;
}
public boolean getResult() {
return result;
}
}
Controller Method
#RequestMapping("/runbatchfile")
public ResultWrapper runbatchFile() {
RunBatchFile rbf = new RunBatchFile();
return rbf.runBatch();
}

I want to implement a methode which allow me to prepare a test

So i want to implement a methode which allow me to prepare a test automatically
a test is an set of question and the test must be preparated automatically
So the questions will be displayed in random manner from the database.
I know that the sql query is like this :
SELECT q FROM Question ORDER BY RAND() LIMIT ...;
this the package who concern all services offered by Class Test
package tn.esen.services.gestion.test;
#Stateless
public class GestionTest implements GestionTestRemote, GestionTestLocal {
#PersistenceContext
private EntityManager entityManager;
/**
* Default constructor.
*/
public GestionTest() {
// TODO Auto-generated constructor stub
}
#Override
public boolean addTest(Test test) {
try {
entityManager.persist(test);
return true;
} catch (Exception e) {
System.err.println("Impossible de créer un Test");
} return false;
}
#Override
public boolean updateTest(Test test) {
try {
entityManager.merge(test);
return true;
} catch (Exception e) {
System.err.println("Impossible de mettre à jour un test");
} return false;
}
#Override
public boolean deleteTest(Test test) {
try {
entityManager.remove(entityManager.merge(test));
return true;
} catch (Exception e) {
System.err.println("Impossible de supprimer un test");
} return false;
}
#Override
public List<Test> readAllTest() {
String jpql = "select t from Test t ";
Query query = entityManager.createQuery(jpql);
return query.getResultList();
}
#Override
public Test findTestById(Integer id) {
return (Test) entityManager.find(Test.class, id);
}
#Override
public List<Test> findAllTestByCandidat(Candidat candidat) {
Query query=entityManager.createQuery("select distinct t from Test t join t.resultats r where r.candidat=:cand");
query.setParameter("cand", candidat);
return query.getResultList();

Solution
Assume you have a Question Entity for your Question Table, the fetch is very easy, just fetch any (number_of_questions) from a list of questions in the question table at RANDOM.
public List<Question> prepareRandomTest(int number_of_questions){
String sql = "SELECT * FROM question ORDER BY RANDOM() LIMIT "+number_of_questions;
SQLQuery query = session.createSQLQuery(sql);
query.addEntity(Question.class);
List<Question> results = (List<Question>)query.list();
return result;
}

Create a generic method to combine multiple .close() connection methods

I have these 4 methods which each close a different connection type, meaning each of those has a different input object. Each method calls the close() method on the provided input object. Is there a way to combine those methods into one, taking in a generic object? I have no way to implement an interface on the provided objects or extend them.
import java.sql.Statement;
import javax.jms.Connection;
import javax.mail.Transport;
private void close(Statement stm) {
if(stm == null) {
return;
}
try {
stm.close();
} catch (SQLException ex) {
logger.error("Error while closing statement", ex);
}
}
private void close(java.sql.Connection con) {
if(con == null) {
return;
}
try {
con.close();
} catch (SQLException ex) {
logger.error("Error while closing connection", ex);
}
}
private void close(javax.jms.Connection con) {
if(con == null) {
return;
}
try {
con.close();
} catch(JMSException ex) {
logger.error("Error while closing JMS connection", ex);
}
}
private void close(Transport transport) {
if(transport == null) {
return;
}
try {
transport.close();
} catch (MessagingException ex) {
logger.error("Error while closing mail transport", ex);
}
}
EDIT:
Thank you for your answers regarding Java 1.7. Unfortunately our servers are running Java 1.6, so is there any solution for that?

You can use reflection.
First sample give you support for try() with resources:
#Test
public void testRes() throws Exception {
try(ClosableWrapper<StringWriter> rs = new ClosableWrapper<>(new StringWriter())){
Writer wr = rs.getResource();
}
}
static class ClosableWrapper<T> implements AutoCloseable{
private T resource;
private String closeMethod = "close";
public ClosableWrapper(T resource) {
this.resource = resource;
}
public ClosableWrapper(T resource, String closeMethod) {
this.resource = resource;
this.closeMethod = closeMethod;
}
public T getResource() {
return resource;
}
#Override
public void close() throws Exception {
if(resource!=null){
Method m = resource.getClass().getMethod(closeMethod);
m.invoke(resource);
}
}
}
or just one method:
public void close(Object resource) throws Exception {
if(resource!=null){
Method m = resource.getClass().getMethod("close");
m.invoke(resource);
}
}

Assuming these are your classes, use the AutoCloseable interface and put them in a try-with-resource.