|
This page contains an archived post to the Java Answers Forum made prior to February 25, 2002.
If you wish to participate in discussions, please visit the new
Artima Forums.
Message:
JTable -- populate at runtime
Posted by Pritam on May 04, 2001 at 7:10 AM
Kishori,
This is fine for one-time population of a table.
Suppose I have an applet with a JTable and a textfield.
Depending on the value of the textfield the table is to be populated.For the first time the solution provided by you will work fine.
But when I change the value in the text field,how do I clear the rows in the table and populate it with new data assuming that the columncount and type remains the same. Pritam
> Yes, the resultset of a query can be populated in a JTable. There are two ways of doing this.
> 1) You can store all the data from resultset in a two dimensional array of Object and then pass this array to Jtable constructor.
> Object[]][] data ;;
> // Populate the data array from resultset
> String[] columnLabels = { "col1", "col2"... } ;
> JTable tt = new JTable ( data, columnLabels )
> 2) You can build your own table model which will be queried by JTable for data in each cell.How to build a table model? Table model will be a class which inherits AbstractTableModel class and will override at least three of its methods viz.
> public int getColumnCount ( ) ;
> public int getRowCount ( ) ;
> public Object getValueAt ( int rowNo, int coulnmNo ) ;
> If you just override these three methods then your column's header will be given as A, B, C ... . So if you want to supply your own column headers ( certainly you would ) then you need to override another method
> public String getColumnName ( int col ) ;
> By methods names you can guess what do you need to write in those methods. However, I will give you hints for every methods. Your table model class will be as follows.
> class MalaTableModel extends AbstractTableModel {
> private ResultSet rs ;
> private ResultSetMetaData rsmd ; // You need to populate it
> public MalaTableModel ( ResultSet rs ) {
> this.rs = rs ;
> // Get the meta data for result set here
> }
> public int getRowCount ( ) {
> // If you are using ODBC2.0 then you can get the
> // row count from a result set as follows
> rs.last ( ) ;
> int rowCount = rs.getRow ( ) ;
> return rowCount ;
> // if rs.last ( ) is not supported then
> /*
> Keep scrolling from 1st to last row and return the total
> no of rows
> */
> }
> public int getColumnCount ( ) {
> return rsmd.getColumnCount ( ) ;
> }
> public getValueAt ( int row, int col ) {
> // Scroll the result set to the row
> rs.absolute ( row + 1 ) ;
> return rs.getObject ( col + 1 ) ;
> }
> public String getColumnName ( int col ) {
> return rsmd.getColumnName ( col + 1 ) ;
> }
> } > //////////////////////////////////////////////////////////////////
> I haven't used try-catch in above code. But you need to use them
> //////////////////////////////////////////////////////////////// > Before using this table model you need to connect to database and fetch the resultset. Then you can write the following code
> MalaTableModel mtm = new malaTableModel ( your_result_set ) ;
> // Don't forget to populate the MetaResultSet object in constructor of
> // your table model
> // Create JTable
> JTable jt = new JTable ( mtm ) ;
> Now you can add this table jt anywhere you want and your data from resultset will be displayed in this table.
> Note: Your resultset has to be scrollable in both direction ( forwatrd and backward ) . > Thanx
> Kishori
Replies:
|
