Question

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.