Setting a new team for a user works, although have not used live github code.

src/main/java/nl/andrewlalis/model/database/DbHelper.java

@@ -53,4 +53,16 @@ public class DbHelper {
         return studentTeams;
     }
 
+    /**
+     * Executes some transaction content.
+     * @param content The content to execute.
+     */
+    public static void executeTransactionContent(TransactionContent content) {
+        Session session = DbUtil.getSessionFactory().openSession();
+        Transaction tx = session.beginTransaction();
+        content.doTransaction(session);
+        tx.commit();
+        session.close();
+    }
+
 }

src/main/java/nl/andrewlalis/model/database/TransactionContent.java

@@ -0,0 +1,16 @@
+package nl.andrewlalis.model.database;
+
+import org.hibernate.Session;
+
+/**
+ * Defines a series of operations done within a transaction.
+ */
+public interface TransactionContent {
+
+    /**
+     * Performs a transaction. Implement this method by updating, inserting, or deleting entities.
+     * @param session The session in which operations are being done.
+     */
+    void doTransaction(Session session);
+
+}

src/main/java/nl/andrewlalis/ui/control/listeners/management_view/student_actions/SetTeamListener.java

@@ -2,9 +2,12 @@ package nl.andrewlalis.ui.control.listeners.management_view.student_actions;
 
 import nl.andrewlalis.model.Student;
 import nl.andrewlalis.model.StudentTeam;
+import nl.andrewlalis.model.database.DbHelper;
 import nl.andrewlalis.ui.control.listeners.management_view.TableRowListener;
+import nl.andrewlalis.ui.view.ManagementView;
 import nl.andrewlalis.ui.view.dialogs.TeamChooserDialog;
 import nl.andrewlalis.ui.view.table_models.StudentTableModel;
+import nl.andrewlalis.ui.view.table_models.StudentTeamTableModel;
 
 import javax.swing.*;
 import java.awt.event.ActionEvent;
@@ -17,8 +20,20 @@ import java.awt.event.ActionEvent;
  */
 public class SetTeamListener extends TableRowListener {
 
-    public SetTeamListener(JTable table) {
+    /**
+     * The teamModel is a reference to the current team model for student teams.
+     */
+    private StudentTeamTableModel teamModel;
+
+    /**
+     * A reference to the management view, which is used to tell the management view when to update the models.
+     */
+    private ManagementView managementView;
+
+    public SetTeamListener(ManagementView managementView, JTable table, StudentTeamTableModel teamModel) {
         super(table);
+        this.managementView = managementView;
+        this.teamModel = teamModel;
     }
 
     @Override
@@ -26,6 +41,26 @@ public class SetTeamListener extends TableRowListener {
         StudentTableModel model = (StudentTableModel) this.getTable().getModel();
         Student student = model.getStudentAt(this.getSelectedRow());
 
-        StudentTeam chosenTeam = (StudentTeam) new TeamChooserDialog(SwingUtilities.getWindowAncestor(this.getTable())).getSelectedTeam();
+        StudentTeam[] teams = new StudentTeam[this.teamModel.getRowCount()];
+        this.teamModel.getTeams().toArray(teams);
+
+        StudentTeam chosenTeam = (StudentTeam) new TeamChooserDialog(
+                SwingUtilities.getWindowAncestor(this.getTable()),
+                teams
+        ).getSelectedTeam();
+
+        // Perform the updates to the database here.
+        DbHelper.executeTransactionContent(session -> {
+            student.getAssignedTeam().removeMember(student);
+            session.update(student.getAssignedTeam());
+
+            chosenTeam.addMember(student);
+            session.update(chosenTeam);
+
+            student.assignToTeam(chosenTeam);
+            session.update(student);
+        });
+
+        this.managementView.updateModels();
     }
 }

src/main/java/nl/andrewlalis/ui/view/ManagementView.java

@@ -5,6 +5,7 @@ import nl.andrewlalis.model.database.DbHelper;
 import nl.andrewlalis.model.database.DbUtil;
 import nl.andrewlalis.ui.control.listeners.management_view.PopupSelector;
 import nl.andrewlalis.ui.control.listeners.management_view.student_actions.RemoveFromCourseListener;
+import nl.andrewlalis.ui.control.listeners.management_view.student_actions.SetTeamListener;
 import nl.andrewlalis.ui.view.components.DetailPanel;
 import nl.andrewlalis.ui.view.table_models.StudentTableModel;
 import nl.andrewlalis.ui.view.table_models.StudentTeamTableModel;
@@ -63,6 +64,9 @@ public class ManagementView extends AbstractView {
 
         this.detailPanel = new DetailPanel();
 
+        this.studentsModel = new StudentTableModel(DbHelper.getStudents());
+        this.studentTeamModel = new StudentTeamTableModel();
+
         contentPane.add(this.buildCommandPanel(), BorderLayout.WEST);
         contentPane.add(this.detailPanel, BorderLayout.EAST);
         contentPane.add(this.buildOverviewPanel(), BorderLayout.CENTER);
@@ -140,17 +144,26 @@ public class ManagementView extends AbstractView {
      */
     private JPanel buildStudentsTablePanel() {
         // Initialize the model, table, and a surrounding scroll pane.
-        this.studentsModel = new StudentTableModel(DbHelper.getStudents());
-
         JTable table = new JTable(this.studentsModel);
         table.setFillsViewportHeight(true);
         table.getSelectionModel().addListSelectionListener(listSelectionEvent -> {
-            detailPanel.setDetailableEntity(studentsModel.getStudentAt(table.getSelectedRow()));
+            int row = table.getSelectedRow();
+            if (row >= 0 && row < studentsModel.getRowCount()) {
+                detailPanel.setDetailableEntity(studentsModel.getStudentAt(row));
+            }
         });
+
+        // A context menu for the table.
         JPopupMenu menu = new JPopupMenu("Menu");
+        // Item for setting a student's team.
+        JMenuItem setTeamItem = new JMenuItem("Set team");
+        setTeamItem.addActionListener(new SetTeamListener(this, table, this.studentTeamModel));
+        menu.add(setTeamItem);
+        // Item for removing a student from the course.
         JMenuItem removeItem = new JMenuItem("Remove from course");
         removeItem.addActionListener(new RemoveFromCourseListener(table));
         menu.add(removeItem);
+
         menu.addPopupMenuListener(new PopupSelector(table));
         table.setComponentPopupMenu(menu);
 
@@ -161,7 +174,8 @@ public class ManagementView extends AbstractView {
      * @return A JPanel to be put into a tab for display of a list of student teams.
      */
     private JPanel buildStudentTeamsTablePanel() {
-        this.studentTeamModel = new StudentTeamTableModel(DbHelper.getStudentTeams());
+        // Make sure that the model has the latest student teams.
+        this.studentTeamModel.setStudentTeamsList(DbHelper.getStudentTeams());
 
         JTable table = new JTable(this.studentTeamModel);
         table.setFillsViewportHeight(true);

src/main/java/nl/andrewlalis/ui/view/dialogs/TeamChooserDialog.java

@@ -1,18 +1,84 @@
 package nl.andrewlalis.ui.view.dialogs;
 
+import nl.andrewlalis.model.StudentTeam;
 import nl.andrewlalis.model.Team;
 
 import javax.swing.*;
 import java.awt.*;
 
+/**
+ * With this dialog, a user can choose from a list of teams. This works for any type of team.
+ * The user should have the option to create a new team.
+ */
 public class TeamChooserDialog extends JDialog {
 
-    public TeamChooserDialog(Window parent) {
+    /**
-        super(parent);
+     * The combo box used in selecting a team. Will be populated by all team numbers.
+     */
+    private JComboBox<Integer> teamChooserBox;
+
+    /**
+     * The team which is selected.
+     */
+    private Team selectedTeam;
+
+    /**
+     * The model containing the list of teams.
+     */
+    private StudentTeam[] teams;
+
+    public TeamChooserDialog(Window parent, StudentTeam[] teams) {
+        super(parent, "Team Chooser", ModalityType.APPLICATION_MODAL);
+        this.teams = teams;
+        this.setContentPane(this.buildContentPane());
+        this.pack();
+        this.setLocationRelativeTo(null);
+        this.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
+        this.setVisible(true);
     }
 
+    /**
+     * @return The dialog's content pane, containing all user interface elements.
+     */
+    private JPanel buildContentPane() {
+        JPanel contentPane = new JPanel(new BorderLayout());
+
+        contentPane.add(new JLabel("Choose a team."), BorderLayout.NORTH);
+
+        // Main selection panel.
+        // Create a list of numbers to represent the teams.
+        Integer[] teamNumbers = new Integer[this.teams.length];
+        for (int row = 0; row < this.teams.length; row++) {
+            teamNumbers[row] = this.teams[row].getNumber();
+        }
+
+        this.teamChooserBox = new JComboBox<>(teamNumbers);
+        contentPane.add(this.teamChooserBox, BorderLayout.CENTER);
+
+        // Button panel for confirming or cancelling selection.
+        JPanel confirmPanel = new JPanel();
+        JButton doneButton = new JButton("Done");
+        // Add a small action listener to set the selected team and dispose of the dialog.
+        doneButton.addActionListener(actionEvent -> {
+            selectedTeam = teams[teamChooserBox.getSelectedIndex()];
+            dispose();
+        });
+        confirmPanel.add(doneButton);
+
+        JButton cancelButton = new JButton("Cancel");
+        // Add a small action listener to dispose of the dialog and return the null selected team.
+        cancelButton.addActionListener(actionEvent -> dispose());
+        confirmPanel.add(cancelButton);
+        contentPane.add(confirmPanel, BorderLayout.SOUTH);
+
+        return contentPane;
+    }
+
+    /**
+     * @return The team which was selected by the user.
+     */
     public Team getSelectedTeam() {
-        return null;
+        return this.selectedTeam;
     }
 
 }

src/main/java/nl/andrewlalis/ui/view/table_models/StudentTeamTableModel.java

@@ -63,6 +63,13 @@ public class StudentTeamTableModel extends AbstractTableModel {
         return null;
     }
 
+    /**
+     * @return A list of all teams in this model.
+     */
+    public List<StudentTeam> getTeams() {
+        return this.studentTeamsList;
+    }
+
     @Override
     public int getRowCount() {
         return this.studentTeamsList.size();