how to set JTree "ctrl" selection mode to be always enabled

Question

Hello,

I have a JTree that implements multi selection logic.

This works great when I do all my selections using the mouse + Ctrl key pressed. If user makes selections with the Ctrl key unpressed it breaks my logic.

I can't really see why it breaks but I think that a possible solution is to always indicate the TreeSelectionModel that the selection has been make with the Ctrl key pressed.

What would you suggest ?

Answer 1

I think I've found the solution

You will need to extend JTree and DefaultTreeSelectionModel.

JTree relevant methods:

/////////////////////////////////////////////////////
/////////////////////////////////////////////////////
/// Implement selection using "adding" only logic. //
/////////////////////////////////////////////////////
/////////////////////////////////////////////////////

@Override
public void setSelectionPath(TreePath path) {

 System.out.println("MLDebugJTree: setSelectionPath(" + path + ")");

 addSelectionPath(path);

 return;
 //super.setSelectionPath(path);
}

@Override
public void setSelectionPaths(TreePath[] paths) {

 System.out.println("MLDebugJTree: setSelectionPaths(" + paths + ")");

 addSelectionPaths(paths);

 return;
}

@Override
public void setSelectionRow(int row) {

 System.out.println("MLDebugJTree: setSelectionRow(" + row + ")");

 addSelectionRow(row);

 return;
 //super.setSelectionRow(row);
}

@Override
public void setSelectionRows(int[] rows) {

 System.out.println("MLDebugJTree: setSelectionRows(" + rows + ")");

 addSelectionRows(rows);

 return;
 //super.setSelectionRows(rows);
}

DefaultSelectionModel relevant methods :

package com.ml.tree2.model.impl;

import javax.swing.tree.DefaultTreeSelectionModel;
import javax.swing.tree.TreePath;

public class MLTreeSelectionModel extends DefaultTreeSelectionModel {
private static final long serialVersionUID = -4270031800448415780L;

@Override
public void addSelectionPath(TreePath path) {
 // Don't do overriding logic here because addSelectionPaths is ultimately called.
 super.addSelectionPath(path);
}

@Override
public void addSelectionPaths(TreePath[] paths) {
 if(paths != null) {
  for(TreePath path : paths) {

   TreePath[] toAdd = new TreePath[1];
   toAdd[0] = path;

   if (isPathSelected(path)) {
    // If path has been previously selected REMOVE THE SELECTION.
    super.removeSelectionPaths(toAdd);
   } else {
    // Else we really want to add the selection...
    super.addSelectionPaths(toAdd);
   }
  }
 }
}

HTH.