How do I drag and drop a row in a JTable?

Question

I'm trying to install microk8s, using Ansible.

I get the error : "No snap matching 'microk8s' available"

I'm using WSL 2 (Ubuntu 20.04), and snap version 2.44.3+20.04.

My configuration:

- name: Install microk8s
  snap:
    name:
      - microk8s
    classic: yes
  become: true

Does anyone know how to fix this?

Solution 1

Check out the drag and drop section of the Java Tutorial. There are some examples on how to implement this for JTable.

Solution 2

The following allows JTable re-ordering of a single dragged row:

  table.setDragEnabled(true);
  table.setDropMode(DropMode.INSERT_ROWS);
  table.setTransferHandler(new TableRowTransferHandler(table)); 

Your TableModel should implement the following to allow for re-ordering:

public interface Reorderable {
   public void reorder(int fromIndex, int toIndex);
}

This TransferHandler class handles the drag & drop, and calls reorder() on your TableModel when the gesture is completed.

/**
 * Handles drag & drop row reordering
 */
public class TableRowTransferHandler extends TransferHandler {
   private final DataFlavor localObjectFlavor = new ActivationDataFlavor(Integer.class, "application/x-java-Integer;class=java.lang.Integer", "Integer Row Index");
   private JTable           table             = null;

   public TableRowTransferHandler(JTable table) {
      this.table = table;
   }

   @Override
   protected Transferable createTransferable(JComponent c) {
      assert (c == table);
      return new DataHandler(new Integer(table.getSelectedRow()), localObjectFlavor.getMimeType());
   }

   @Override
   public boolean canImport(TransferHandler.TransferSupport info) {
      boolean b = info.getComponent() == table && info.isDrop() && info.isDataFlavorSupported(localObjectFlavor);
      table.setCursor(b ? DragSource.DefaultMoveDrop : DragSource.DefaultMoveNoDrop);
      return b;
   }

   @Override
   public int getSourceActions(JComponent c) {
      return TransferHandler.COPY_OR_MOVE;
   }

   @Override
   public boolean importData(TransferHandler.TransferSupport info) {
      JTable target = (JTable) info.getComponent();
      JTable.DropLocation dl = (JTable.DropLocation) info.getDropLocation();
      int index = dl.getRow();
      int max = table.getModel().getRowCount();
      if (index < 0 || index > max)
         index = max;
      target.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
      try {
         Integer rowFrom = (Integer) info.getTransferable().getTransferData(localObjectFlavor);
         if (rowFrom != -1 && rowFrom != index) {
            ((Reorderable)table.getModel()).reorder(rowFrom, index);
            if (index > rowFrom)
               index--;
            target.getSelectionModel().addSelectionInterval(index, index);
            return true;
         }
      } catch (Exception e) {
         e.printStackTrace();
      }
      return false;
   }

   @Override
   protected void exportDone(JComponent c, Transferable t, int act) {
      if ((act == TransferHandler.MOVE) || (act == TransferHandler.NONE)) {
         table.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
      }
   }

}

Solution 3

I like Soley's modifications, but his code relies on an external library, and I'm not sure where he got it from, so I re-wrote it so that you don't need the TableUtil class...

 @Override
   public boolean importData(TransferHandler.TransferSupport info) {
     JTable target = (JTable) info.getComponent();
        JTable.DropLocation dl = (JTable.DropLocation) info.getDropLocation();
        int index = dl.getRow();
        int max = table.getModel().getRowCount();
        if (index < 0 || index > max) {
            index = max;
        }
        target.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));

        try {
            Integer rowFrom = (Integer) info.getTransferable().getTransferData(localObjectFlavor);
            if (rowFrom != -1 && rowFrom != index) {

                int[] rows = table.getSelectedRows();
                int iter = 0;
                for (int row : rows) {
                    if (index > row) {
                        index--;
                        ((Reorderable) table.getModel()).reorder(row - iter, index);
                    }

                    else {
                        ((Reorderable) table.getModel()).reorder(row, index);
                    }
                    index++;
                    iter++;
                }

                target.getSelectionModel().addSelectionInterval(index, index);

                return true;
            }

      } catch (Exception e) {
            String error = e.getMessage();
            JOptionPane.showMessageDialog(null, error, "Error", JOptionPane.ERROR_MESSAGE);
      }
      return false;
   }

Comments

[a2f0]

For anybody having trouble with this on Ubuntu 20 (without WSL), make sure to run the command to install the collection ansible-galaxy collection install community.general

[Koobz]

I was getting exceptions upon transfer that I fixed by changing localObjectFlavor to: private final DataFlavor localObjectFlavor = new DataFlavor(Integer.class, "Integer Row Index");

[Stephan]

+1 But unfortunately this will not work for multiple row selection.

[pstanton]

+1 - a couple of simple modifications and this works perfectly !

[David]

Nice example! Although I noticed a bug in exportDone. If you drag the selected value outside the component and release the curser will keep the "copy icon". I corrected this by modifying the if statement in exportDone to "act == TransferHandler.MOVE || act == TransferHandler.NONE".

[Ignas2526]

Great code. One problem I had with it, is that I kept getting java.lang.ClassCastException: java.lang.Integer cannot be cast to java.io.InputStream error. Using instead localObjectFlavor = new ActivationDataFlavor(Integer.class, "application/x-java-Integer;class=java.lang.Integer", "Integer Row Index") solved the error.

[ImJustACowLol]

I find the usage of TransferHandler highly complicated and unnecessary... I would propose the solution that makes use of Mouse(Motion)Listeners: stackoverflow.com/questions/58043707/…

[MARCOS GARCES]

I get: nsenter: failed to parse pid: '-a'

[mvmn]

What is TableUtil?

[Soley]

It is a class that make working with rows simple. The method name is describe what we will receive from them. You can replace them by your own methods, or use Table's own methods.