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Thread: JavaFX - TableView not displaying ObservableList correctly.

  1. #1
    Join Date
    Feb 2019
    Posts
    1

    Question JavaFX - TableView not displaying ObservableList correctly.

    I originally had this application working, but after refactoring, it's got a bug. There are 2 classes involved, fairly simple. Controller and DBController. Controller is responsible for handling the User Interface. DBController is responsible for accessing the database supplied, and returning the necessary objects back to Controller for processing.

    Expected Results


    Actual Results


    Previously, Controller.connect() handled both the database access, ResultSet processing and the UI updating. Here was it's code. (this code produces the desired results)
    Controller.connect()
    PHP Code:
        private void connect() {
            
    StringBuilder dbUrl = new StringBuilder("jdbc:sqlite:");
            if (
    dbUrlTxt.getText().isEmpty()) {
                new 
    Alert(Alert.AlertType.ERROR"Database url must be specified.").showAndWait();
            } else {
                try {
                    
    connection getConnection(dbUrl.append(dbUrlTxt.getText()).toString());
                } catch (
    SQLException e) {
                    
    e.printStackTrace();
                }
                
    String tableQuery "SELECT * FROM sqlite_master WHERE type='table' ORDER BY name";
                try (
    PreparedStatement tableQueryPS connection.prepareStatement(tableQuery)) {
                    
    ResultSet tableNames tableQueryPS.executeQuery();

                    while (
    tableNames.next()) {

                        
    Tab tab = new Tab(tableNames.getString("name"));
                        
    tabPane.getTabs().add(tab);

                        
    TableView<ObservableListtableView = new TableView<>();
                        
    tab.setContent(tableView);

                        
    String dataQuery "SELECT * from " tableNames.getString("name");
                        
    ResultSet tableValues connection.createStatement().executeQuery(dataQuery);

                        for (
    int i 0tableValues.getMetaData().getColumnCount(); i++) {
                            final 
    int j i;
                            
    int dataValue tableValues.getMetaData().getColumnType(1);
                            
    // I need to use some generics here on the TableColumn to get rid of the Unchecked call to setCellValueFactory()
                            
    TableColumn tableColumn = new TableColumn(tableValues.getMetaData().getColumnName(1));
                            if (
    dataValue == 4) {
                                
    tableColumn.setCellValueFactory((Callback<TableColumn.CellDataFeatures<ObservableListInteger>, ObservableValue<String>>) param ->
                                        
    new SimpleStringProperty(param.getValue().get(j).toString()));
                            } else if (
    dataValue == 7) {
                                
    tableColumn.setCellValueFactory((Callback<TableColumn.CellDataFeatures<ObservableListDouble>, ObservableValue<String>>) param ->
                                        
    new SimpleStringProperty(param.getValue().get(j).toString()));
                            } else if (
    dataValue == 12) {
                                
    tableColumn.setCellValueFactory((Callback<TableColumn.CellDataFeatures<ObservableListString>, ObservableValue<String>>) param ->
                                        
    new SimpleStringProperty(param.getValue().get(j).toString()));
                            }
                            
    tableView.getColumns().addAll(tableColumn);
                        }

                        
    ObservableList<ObservableListdata FXCollections.observableArrayList();

                        while (
    tableValues.next()) {
                            
    ObservableList<Stringrow FXCollections.observableArrayList();
                            for (
    int i 1<= tableValues.getMetaData().getColumnCount(); i++) {
                                
    row.add(tableValues.getString(i));
                            }
                            
    data.add(row);
                        }
                        
    tableValues.close();
                        
    tableView.getItems().addAll(data);
                    }
                    
    tableNames.close();

                } catch (
    SQLException tableQueryException) {
                    
    System.err.println(tableQueryException.toString());
                }
                
    connectBtn.setDisable(true);
                
    disconnectBtn.setDisable(false);
                
    addBtn.setDisable(false);
                
    updateBtn.setDisable(false);
                
    deleteBtn.setDisable(false);
                
    saveBtn.setDisable(false);
            }
        } 
    Now Controller.handleConnect() is in charge, along with an instance of DBController

    Controller.handleConnect()
    PHP Code:
        private void handleConnect() {
            if (
    dbUrlTxt.getText().isEmpty() && !Main.debug) {
                new 
    Alert(Alert.AlertType.ERROR"Database url must be specified.").showAndWait();
            } else {
                
    dbController = new DBController();
                
    dbController.connect(dbUrlTxt.getText());
                
    toggleButtons();

                
    //process table
                
    List<StringtableNames dbController.queryTables();

                
    tableNames.forEach(tableName -> {
                    if (
    Main.debug) {
                        
    System.out.println(tableName " table");
                        
    System.out.println("-------------------------");
                    }
                    
    Tab tab = new Tab(tableName);
                    
    tabPane.getTabs().add(tab);

                    
    TableView<ObservableListtableView = new TableView<>();
                    
    tab.setContent(tableView);

                    
    //process columns
                    
    Map<StringStringcolumns dbController.queryColumns(tableName);
                    if (
    Main.debug) {
                        
    System.out.println("Column Name, Column Type");
                        
    System.out.println("-------------------------");
                    }
                    
    columns.forEach((columnNamecolumnType) -> {
                        if (
    Main.debug) { System.out.println(columnName ", " columnType); }
                        
    TableColumn tableColumn = new TableColumn(columnName);
                        switch (
    columnType) {
                            case 
    "INTEGER":
                                
    tableColumn.setCellValueFactory((Callback<TableColumn.CellDataFeatures<ObservableListInteger>, ObservableValue<String>>) param ->
                                        
    new SimpleStringProperty(param.getValue().toString()));
                            case 
    "REAL":
                                
    tableColumn.setCellValueFactory((Callback<TableColumn.CellDataFeatures<ObservableListDouble>, ObservableValue<String>>) param ->
                                        
    new SimpleStringProperty(param.getValue().toString()));
                            case 
    "TEXT":
                            case 
    "NONE":
                            default:
                                
    tableColumn.setCellValueFactory((Callback<TableColumn.CellDataFeatures<ObservableListString>, ObservableValue<String>>) param ->
                                        
    new SimpleStringProperty(param.getValue().toString()));
                        }
                        
    tableView.getColumns().addAll(tableColumn);
                    });
                    if (
    Main.debug) { System.out.println(); }

                    
    // process rows
                    
    ObservableList<ObservableListrows dbController.queryRows(tableName);
                    if (
    Main.debug) {
                        
    rows.forEach(row -> System.out.println(row));
                        
    System.out.println();
                    }
                    
    tableView.getItems().addAll(rows);
                });
            }
        } 
    DBController
    PHP Code:
    import javafx.collections.FXCollections;
    import javafx.collections.ObservableList;
    import javafx.scene.control.Alert;

    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.SQLException;
    import java.sql.ResultSet;
    import java.sql.PreparedStatement;
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;

    class 
    DBController {

        private 
    Connection connection;

        
    Connection getConnection() {
            return 
    connection;
        }

        
    void connect(String databaseURL) {
            
    Connection connection null;
            
    StringBuilder dbUrl = new StringBuilder("jdbc:sqlite:");
            
    dbUrl.append(databaseURL);
            try {
                if (
    Main.debug) {
                    
    connection DriverManager.getConnection("jdbc:sqlite:C:/products.sqlite");
                    
    System.out.println("Connection to C:/products.sqlite established\n");
                } else {
                    
    connection DriverManager.getConnection(dbUrl.toString());
                }
            } catch (
    SQLException connectionException) {
                
    System.err.println(connectionException.toString());
                new 
    Alert(Alert.AlertType.ERROR"There was a problem connecting to the database. Please check that the url is correct.").showAndWait();
            }
            
    this.connection connection;
        }

        List<
    StringqueryTables() {
            
    String statement "SELECT * FROM sqlite_master WHERE type='table' ORDER BY name";
            List<
    StringtableNames = new ArrayList<>();
            try (
    PreparedStatement preparedStatement connection.prepareStatement(statement)) {
                
    ResultSet resultSet preparedStatement.executeQuery();
                while (
    resultSet.next()) {
                    
    tableNames.add(resultSet.getString("name"));
                }
                
    resultSet.close();
            } catch (
    SQLException tableQueryException) {
                
    System.err.println(tableQueryException.toString());
            }
            return 
    tableNames;
        }

        
    Map<StringStringqueryColumns(String tableName) {
            
    String statement "PRAGMA table_info(" tableName ")";
            
    Map<StringStringcolumns = new HashMap<>();
            try (
    PreparedStatement preparedStatement connection.prepareStatement(statement)) {
                
    ResultSet resultSet preparedStatement.executeQuery();
                while (
    resultSet.next()) {
                    
    columns.put(resultSet.getString("name"), resultSet.getString("type"));
                }
                
    resultSet.close();
            } catch (
    SQLException columnQueryException) {
                
    System.err.println(columnQueryException.toString());
            }
            return 
    columns;
        }


        
    ObservableList<ObservableListqueryRows(String tableName) {
            
    String statement "SELECT * from " tableName;
            
    ObservableList<ObservableListrows FXCollections.observableArrayList();
            try (
    PreparedStatement preparedStatement connection.prepareStatement(statement)) {
                
    ResultSet resultSet preparedStatement.executeQuery();
                while (
    resultSet.next()) {
                    
    ObservableList<Stringrow FXCollections.observableArrayList();
                    for (
    int i 1<= resultSet.getMetaData().getColumnCount(); i++) {
                        
    row.add(resultSet.getString(i));
                    }
                    
    rows.add(row);
                }
                
    resultSet.close();
            } catch (
    SQLException rowQueryException) {
                
    System.err.println(rowQueryException.toString());
            }
            return 
    rows;
        }

        
    void disconnect() {
            
    this.connection null;
            if (
    Main.debug) { System.out.println("Connection Closed"); }
        }


    I know this is fairly complicated but please, any help would be greatly appreciated. I've been trying to fix this bug for over 2 weeks now, no one seems to be able to help. Full source code can be found here. https://github.com/elsheepo/SQLite-Database-Manager

  2. #2
    Join Date
    Jun 1999
    Location
    Eastern Florida
    Posts
    3,853

    Re: JavaFX - TableView not displaying ObservableList correctly.

    The contents of the cells in the table look like the String returned by a List's toString method. The list has three elements.
    The same String is added to each of the cells on a row.

    Can the code get at the items in the list and add the first item in the list to the first column, the second item to the second column, etc?
    Norm

  3. #3
    2kaud's Avatar
    2kaud is offline Super Moderator Power Poster
    Join Date
    Dec 2012
    Location
    England
    Posts
    6,768

    Re: JavaFX - TableView not displaying ObservableList correctly.

    but after refactoring, it's got a bug
    I can't advise on specifics as I don't use Java. However in general when a program in any language doesn't do what it is expected then the first port of call is the debugger to trace through the program to find where it deviates from that expected. When this happens then you know where is the problem. Just looking at the code isn't going to tell you what's actually happening whereas tracing through the code will.
    All advice is offered in good faith only. All my code is tested (unless stated explicitly otherwise) with the latest version of Microsoft Visual Studio (using the supported features of the latest standard) and is offered as examples only - not as production quality. I cannot offer advice regarding any other c/c++ compiler/IDE or incompatibilities with VS. You are ultimately responsible for the effects of your programs and the integrity of the machines they run on. Anything I post, code snippets, advice, etc is licensed as Public Domain https://creativecommons.org/publicdomain/zero/1.0/ and can be used without reference or acknowledgement. Also note that I only provide advice and guidance via the forums - and not via private messages!

    C++17 Compiler: Microsoft VS2019 (16.2.2)

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