Question

I am making a java project and i am using JTable.
The thing i want to do is link a popupmenu to the jtable. The popupmenu has four different items. Some of the items need to know selected row in jtable. The problem is in selectRow -function. i cannot get a function to return a proper row. i click on a jtable with right mouse button and i get a popupmenu popped in the same column i clicked as it should be. but when i use addSelectedRow or removeSelectedRow -functions (in menuItem with label “addSelected” or “deleteSelected”) and any row(s) is no selected i use selectRow -function to find a row i am clicking at with right mousebutton. Seems that rowAtPoint(Point p) cant not just find a right row. It returns eather 0 or -1. I have been struggling with this problem almost a week so pleace pimp my code 😀 i hope code is clean enough 😀

<–Edited–>
http://painkiller.comlu.com/images/1.jpg

Here is a screenshot of a problem.
JTable has allways at least one row. I click arbitrary any row (at this situation second row). Row is not selected by purpose. Now if i press “Lisää valittu” – which means “Add selected“, function selectRow() will be called.

/**Locations

jTbl.getLocation(): java.awt.Point[x=0,y=0]
e.getPoints() java.awt.Point[x=4,y=8]
SwingUtilities.convertPoint(e.getComponent(), e.getPoint(), jTbl) java.awt.Point[x=350,y=31]

first i tried e.getPoint()
* e.getPoints() -> java.awt.Point[x=4,y=8]
returned row index number from rowAtPoint(): 0

then i tried SwingUtilities.convertPoint()
* SwingUtilities.convertPoint(tablePopMenu, e.getPoint(), jTbl); -> java.awt.Point[x=28,y=10]
returned row index number from rowAtPoint(): 2

so it seems to work but sometimes function throws -1 or 0. (need to ckeck out that bug) but mostly works pritty good.

<– –>

private void TableMousePressed(java.awt.event.MouseEvent evt) {
        try
        {
            /*
             * The popupmenu content (items) are standart for all tables
             * The label of popupmenu items are used to select proper 
             * command in select case
             * 1. Add selected-> Add only selected row(s)
             * 2. Add all -> Add all rows
             * 3. Delete selected -> Remove only selected row(s)
             * 4. Delete all-> Remove all row(s)
            */

            javax.swing.JTable temp;    //Temporar jTable alien
            String label = ((javax.swing.JMenuItem)evt.getSource()).getText();   //Switch Case


            temp = (javax.swing.JTable)((JPopupMenu)(evt.getComponent().getParent())).getInvoker();
            switch(label)   //Select rigt method by jMenuItem.getText() method (the label of menu item)            {
                case "Add selected":
                    addSelectedRow(evt, temp);
                    break;
                case "Add all":
                    addAllRows(temp);
                    break;
                case "Delete selected":
                    removeSelectedRow(evt, temp);
                    break;
                case "Delete all":
                    removeAllRows(temp);
                    break;
            }            
        }
        catch(Exception ex){ex.printStackTrace();}
    }

    /**
     * @param e - MouseEvent
     * @param jTbl - JTable which will be used
     */
    private void addSelectedRow(java.awt.event.MouseEvent e, javax.swing.JTable jTbl){
        if(jTbl.getSelectedRow() == -1){ //If no row(s) is selected 
            selectRow(e, jTbl); //select row
        }  
        int cellCount = jTbl.getModel().getColumnCount(); //amount of columns to apply
        int rows[] = jTbl.getSelectedRows(); //amount of rows to apply
        cellCollection = new Object[jTbl.getModel().getColumnCount()]; //Object which contains row and cells. will be added to a jTable as a new row

        for(int row = 0; row < rows.length; row++){ //Creates new row by excisting data
            for(int cell = 0; cell < cellCount; cell++){
                cellCollection[cell] = jTbl.getModel().getValueAt(rows[row], cell);
            }
            ((DefaultTableModel)jTbl.getModel()).addRow(cellCollection); //Adds a new row with data
        }         
    }

    /**
     * @param jTbl - JTable which will be used
     */
    private void addAllRows(javax.swing.JTable jTbl){
        int rowCount = jTbl.getModel().getRowCount(); //Amount of adding rows
        int cellCount = jTbl.getModel().getColumnCount(); //Amount of adding colums
        cellCollection = new Object[jTbl.getModel().getColumnCount()]; //New object which contains a row with columns filled with excisting data in a for-loop

        for(int row = 0; row < rowCount; row++){ 
            for(int cell = 0; cell < cellCount; cell++){
                cellCollection[cell] = jTbl.getModel().getValueAt(row, cell);
            }
            ((DefaultTableModel)jTbl.getModel()).addRow(cellCollection);
        }     
    }

    /**
     * @param e - MouseEvent
     * @param jTbl - JTable which will be used
     */
    private void removeSelectedRow(java.awt.event.MouseEvent e, javax.swing.JTable jTbl){
        if(jTbl.getSelectedRow() == -1){ //If no row(s) is selected
            selectRow(e, jTbl); //selects a row
        }
        int[] rows = jTbl.getSelectedRows(); //Get selected row(s)
        for(int i = rows.length - 1; i >= 0; i--)
            ((DefaultTableModel)jTbl.getModel()).removeRow(rows[i]); //Removes the rows
        getTableToLife(jTbl); //Adds a new empty row if jtable has no rows after removing
    }

    /**
     * @param jTbl - JTable which will be used
     */
    private void removeAllRows(javax.swing.JTable jTbl){
        int rowCount = jTbl.getModel().getRowCount(); //Amount of removing rows
        for(int row = rowCount-1; row >=0; row--){ 
            ((DefaultTableModel)jTbl.getModel()).removeRow(row); //Remove rows
        }
        getTableToLife(jTbl);//Adds a new empty row if jtable has no rows after removing        
    }

    /**
     * @param jTbl - JTable which will be saved
     */
    private void getTableToLife(javax.swing.JTable jTbl){
        if(jTbl.getModel().getRowCount() == 0){ //If jtable has no rows
            int cellCount = jTbl.getModel().getColumnCount(); //How many cells will be added
            cellCollection = new Object[cellCount];
            for(int cell = 0; cell < cellCount; cell++){
                cellCollection[cell] = null; //No new data is required                }   
            ((DefaultTableModel)jTbl.getModel()).addRow(cellCollection); //Adding a new empty row
        }
    }

    /**
     * @param e - Mouse event
     */
    private void selectRow(java.awt.event.MouseEvent e, javax.swing.JTable jTbl)
    {

    //      This is the main problem at the moment

    //    System.out.print("\r " + jTbl.rowAtPoint(e.getPoint()));
    //    ListSelectionModel selector = jTbl.getSelectionModel();
    //    selector.removeSelectionInterval(0, jTbl.getHeight()); //I though it he could help, but no effect (row [0] seems to be selected
    //    int p = jTbl.rowAtPoint(e.getPoint()); //or this function seems to be uncapable to find right row i clicked on jtable
    //    selector.setSelectionInterval(p, p); //returns 0 or -1. reason is unknown

    //    New solution
    ListSelectionModel selector = jTbl.getSelectionModel();
    Point newP = SwingUtilities.convertPoint(tablePopMenu, e.getPoint(), jTbl);


    int p = jTbl.rowAtPoint(newP);
    System.out.print("\rRow number: " + (p));
    if(p <=0)
        selector.setSelectionInterval(p, p);
    else
        selector.setSelectionInterval(p-1, p-1);
    }

Thank you people for saving my day!

Answer 1

I am not entirely sure but it is might be that the getPoint() method of the MouseEvent returns a Point in the coordinate space of the popup menu.

What JTable’s rowAtPoint(p) expects is a Point within the coordinate space of the table.

You can use SwingUtilities.convertPoint() to translate the coordinates.