JTable：选择行时从数据库获取值

Question

I have three files, TopicData, TopicView, TopicTableModel. My program displays a table using values from a database. Right now, when I click on a row, the index of the row is printed. I want to modify the code such that the topicID from my database is printed instead. The value of topicID is stored in the ArrayList but not displayed in the table, so I can't use JTable.getValueAt().

Please advise on how to modify my codes. Thanks in advance.

More information:

1. TopicData takes the data from the database and stores it in an ArrayList.

2. The ArrayList is then passed to TopicTableModel where the data is made suitable to be displayed in JTable.

3. TopicView creates a JTable and takes in the TopicTableModel to generate the JTable.

TopicData.java

public class TopicData {
int id;
String name; 
String date; 
String category;
String user;

public TopicData(){
}

public TopicData(int id, String name, String date, String category, String user) {
    this.id = id;
    this.name = name;
    this.date = date;
    this.category = category;
    this.user = user;
}



public TopicData(String name, String date, String category, String user) {
    this.name = name;
    this.date = date;
    this.category = category;
    this.user = user;
}

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getDate() {
    return date;
}

public void setDate(String date) {
    this.date = date;
}

public String getCategory() {
    return category;
}

public void setCategory(String category) {
    this.category = category;
}

public String getUser() {
    return user;
}

public void setUser(String user) {
    this.user = user;
}


public ArrayList<TopicData> getTopicList(){
    ArrayList<TopicData> topicList = new ArrayList<TopicData>();
    ResultSet rs = null;
    DBController db = new DBController();
    db.setUp("myDatabase");
    String dbQuery = "SELECT topicID, topicName, topicDate, topicCategory, topicUser FROM topicTable ORDER BY topicDate";

    rs = db.readRequest(dbQuery);

    try{
        while(rs.next()){
            int id = rs.getInt("topicID");
            String name = rs.getString("topicName"); 
            String date = rs.getString("topicDate") ; 
            String category = rs.getString("topicCategory");
            String user = rs.getString("topicUser");

            TopicData topic = new TopicData (id, name, date, category, user);
            topicList.add(topic);
        }
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    db.terminate();
    return topicList;
}

TopicTableModel.java

public class TopicTableModel extends AbstractTableModel {

private static final long serialVersionUID = 1L;
private int rowCount, colCount;
private String[] columnNames = {"Name", "Date", "User"};
private Object [][] data;

public TopicTableModel(ArrayList<TopicData> listOfObjects) {
    rowCount = listOfObjects.size();
    colCount = columnNames.length;
    data = new Object[rowCount][colCount];

    for (int i = 0; i < rowCount; i++) {
        //Copy an ArrayList element to an instance of MyObject
        TopicData topic = (listOfObjects.get(i)); 
        data[i][0] = topic.getName();            
        data[i][1] = topic.getDate();
        data[i][2] = topic.getUser();
    }              
} 

@Override
public int getColumnCount() {
    // TODO Auto-generated method stub
    return colCount;
}

@Override
public int getRowCount() {
    // TODO Auto-generated method stub
    return rowCount;
}

@Override
public String getColumnName(int col) {
    return columnNames[col];
}

@Override
public Object getValueAt(int rowIndex, int columnIndex) {
    // TODO Auto-generated method stub
    return data[rowIndex][columnIndex];
}

@Override
public boolean isCellEditable(int rowIndex, int colIndex) {
    return false; //Disallow the editing of any cell
}

}

TopicView.java

private JTable getTable() {
    if (table == null) {
        TopicData topic= new TopicData();
        TopicTableModel tableModel = new TopicTableModel(topic.getTopicList());
        table = new JTable(tableModel);

        table.setShowGrid(false);
        table.setFillsViewportHeight(true);
        table.setBounds(173, 87, 456, 263);
        table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        table.getTableHeader().setReorderingAllowed(false);
        table.getTableHeader().setResizingAllowed(false);
        table.getColumnModel().getColumn(0).setPreferredWidth(500);

        ListSelectionModel rowSM = table.getSelectionModel();
        rowSM.addListSelectionListener(new ListSelectionListener() {
            public void valueChanged(ListSelectionEvent e) {
                //Ignore extra messages.
                if (e.getValueIsAdjusting()) return;

                ListSelectionModel lsm = (ListSelectionModel)e.getSource();
                if (lsm.isSelectionEmpty()) {
                    System.out.println("No rows are selected.");
                } 
                else {
                    int selectedRow = lsm.getMinSelectionIndex();
                    System.out.println("Row " + selectedRow + " is now selected.");
                }
            }
        });
    }
    return table;
}

Answer 1

You're doing it the hard way. Rather than converting TopicData into an array, just have your TableModel read the ArrayList of TopicData objects directly, so each TopicData corresponds to a row.

TopicTableModel.java:

import java.util.ArrayList;

import javax.swing.table.AbstractTableModel;

public class TopicTableModel extends AbstractTableModel {

private static final long serialVersionUID = 1L;
private String[] columnNames = {"Name", "Date", "User"};
private ArrayList<TopicData> data;

public TopicTableModel(ArrayList<TopicData> listOfObjects) {
    data = listOfObjects;
} 

@Override
public int getColumnCount() {
    return columnNames.length;
}

@Override
public int getRowCount() {
    return data.size();
}

@Override
public String getColumnName(int col) {
    return columnNames[col];
}

@Override
public Object getValueAt(int rowIndex, int columnIndex) {
    switch (column) {
    case 0:
        return data.getName();
    case 1:
        return data.getDate();
    case 2:
        return data.getUser();
    default:
        throw new ArrayIndexOutOfBoundsException();
    }
}

@Override
public boolean isCellEditable(int rowIndex, int colIndex) {
    return false; //Disallow the editing of any cell
}

public TopicData getTopic(int row) {
    return data.get(row);
}

}

With a few minor modifications to TopicView.java, you can now get the TopicData for the selected row and print its ID.

TopicView.java:

import javax.swing.JTable;
import javax.swing.ListSelectionModel;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;


public class TopicView {
    JTable table;

    private JTable getTable() {
        if (table == null) {
            TopicData topic= new TopicData();
            final TopicTableModel tableModel = new TopicTableModel(topic.getTopicList());
            table = new JTable(tableModel);

            table.setShowGrid(false);
            table.setFillsViewportHeight(true);
            table.setBounds(173, 87, 456, 263);
            table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
            table.getTableHeader().setReorderingAllowed(false);
            table.getTableHeader().setResizingAllowed(false);
            table.getColumnModel().getColumn(0).setPreferredWidth(500);
            table.setDefaultRenderer(TopicData.class, new TopicDataTableCellRenderer());

            ListSelectionModel rowSM = table.getSelectionModel();
            rowSM.addListSelectionListener(new ListSelectionListener() {
                public void valueChanged(ListSelectionEvent e) {
                    //Ignore extra messages.
                    if (e.getValueIsAdjusting()) return;

                    int row = table.getSelectedRow();
                    if (row < 0) {
                        System.out.println("No rows are selected.");
                    }
                    else {
                        System.out.println("id " + tableModel.getTopic(row).getId() + " is now selected.");
                    }
                }
            });
        }
        return table;
    }
}

Answer 2

You actually have everything right under your nose.

All you need to do is change your TableModel so that it keeps the ArrayList instead of transforming that list into an Object[][] .

Something like this (may have some typo issues):

public class TopicTableModel extends AbstractTableModel {

private static final long serialVersionUID = 1L;
private int rowCount, colCount;
private String[] columnNames = {"ID", "Name", "Date", "User"};
private List<TopicData> listOfObjects;
public TopicTableModel(ArrayList<TopicData> listOfObjects) {
    this.listOfObjects = listOfObjects;
} 

@Override
public int getColumnCount() {
    return columnNames.length;
}

@Override
public int getRowCount() {
    return listOfObjects.size();
}

@Override
public String getColumnName(int col) {
    return columnNames[col];
}

@Override
public Object getValueAt(int rowIndex, int columnIndex) {
    TopicData data = listOfObjects.get(rowIndex);
    switch(columnIndex) {
        case 0:
            return data.getId();
        case 1:
            return data.getName();
        case 2:
            return data.getDate();
        case 3:
            return data.getUser();
    }
    return null;
}

@Override
public boolean isCellEditable(int rowIndex, int colIndex) {
    return false; //Disallow the editing of any cell
}

}

Side effect: you will need to make your TopicData Serializable if you use Java serialization (or other technologies that take advantage of Serializable )