How to fill data in a JTable with database?

Question

I want to display a JTable that display the data from a DataBase table as it is.

Up till now, I have used JTable that displays data from Object [ ][ ].

I know one way to display the data is to first convert the database table into Object [ ][ ] but Is there any other which is easy yet more powerful and flexible.

Answer 1

I would recommend taking the following approach:

• Create a Row class to represent a row read from your ResultSet. This could be a simple wrapper around an Object[].
• Create a List<Row> collection, and subclass AbstractTableModel to be backed by this collection.
• Use a SwingWorker to populate your List<Row> by reading from the underlying ResultSet on a background thread (i.e. within the doInBackground() method). Call SwingWorker's publish method to publish Rows back to the Event Dispatch thread (e.g. every 100 rows).
• When the SwingWorker's process method is called with the latest chunk of Rows read, add them to your List<Row> and fire appropriate TableEvents to cause the display to update.
• Also, use the ResultSetMetaData to determine the Class of each column within the TableModel definition. This will cause them to be rendered correctly (which won't be the case if you simply use a 2D Object[][] array).

The advantage of this approach is that the UI will not lock up when processing large ResultSets, and that the display will update incrementally as results are processed.

EDIT

Added example code below:

/**
 * Simple wrapper around Object[] representing a row from the ResultSet.
 */
private class Row {
  private final Object[] values;

  public Row(Object[] values) {
    this.values = values;
  }

  public int getSize() {
    return values.length;
  }

  public Object getValue(int i) {
    return values[i];
  }
}

// TableModel implementation that will be populated by SwingWorker.
public class ResultSetTableModel extends AbstractTableModel {
  private final ResultSetMetaData rsmd;
  private final List<Row> rows;

  public ResultSetTableModel(ResultSetMetaData rsmd) {
    this.rsmd = rsmd;
    this.rows = new ArrayList<Row>();
  }

  public int getRowCount() {
    return rows.size();
  }

  public int getColumnCount() {
    return rsmd.getColumnCount();
  }

  public Object getValue(int row, int column) {
    return rows.get(row).getValue(column);
  }

  public String getColumnName(int col) {
    return rsmd.getColumnName(col - 1); // ResultSetMetaData columns indexed from 1, not 0.
  }

  public Class<?> getColumnClass(int col) {
    // TODO: Convert SQL type (int) returned by ResultSetMetaData.getType(col) to Java Class.
  }
}

// SwingWorker implementation
new SwingWorker<Void, Row>() {
  public Void doInBackground() {
    // TODO: Process ResultSet and create Rows.  Call publish() for every N rows created.
  }

  protected void process(Row... chunks) {
    // TODO: Add to ResultSetTableModel List and fire TableEvent.
  }
}.execute();

Answer 2

Another powerful and flexible way to display database data in a JTable is to load your query's resulting data into a CachedRowSet, then connect it to the JTable with TableModel adapter.

1. Query ---> Database data ---> RowSet
2. RowSet <--> TableModel adapter <--> JTable

This book by George Reese gives the source code for his class RowSetModel to adapt a RowSet as a TableModel. Worked for me out-of-the-box. My only change was a better name for the class: RowSetTableModel.

A RowSet is a subinterface of ResultSet, added in Java 1.4. So a RowSet is a ResultSet.

A CachedRowSet implementation does the work for you, instead of you creating a Row class, a List of Row objects, and ResultSetMetaData as discussed in other answers on this page.

Sun/Oracle provides a reference implementation of CachedRowSet. Other vendors or JDBC drivers may provide implementations as well.

RowSet tutorial