How to design a checkbox treeviewer using jface

Question

I have designed a checkbox treeviewer using jface but when i run the program it doesnot display any thing on the UI.I am not able to find the where the issue is.Please help me whrer the problem is as I am new to jface.

private void createTreeMenu(Composite parentComposite){

            /*treeItem = new TreeItem(tree, SWT.MULTI | SWT.CHECK | SWT.VIRTUAL |SWT.BORDER );
            treeItem.setText("(1)Test Session");
            treeItem.setImage(new Image(null, TreeViewer.class.getClassLoader().getResourceAsStream("icons/Folder-Main.JPG")));*/

            Composite treeMenu = new Composite(parentComposite, SWT.BORDER);
            treeMenu.setLayout(new GridLayout(1, false));
            treeMenu.setLayoutData(new GridData(GridData.FILL, GridData.FILL, true, true));

            /*tree = new Tree (treeMenu, SWT.MULTI | SWT.CHECK |SWT.VIRTUAL );
            GridData treeGD = new GridData(SWT.FILL, GridData.FILL, true, true);
            tree.setLayoutData(treeGD);*/


            CheckboxTreeViewer treeViewer=new CheckboxTreeViewer(tree);      
            treeViewer.setContentProvider(new FileTreeContentProvider());
            treeViewer.setLabelProvider(new FileTreeLabelProvider1());       
            treeViewer.setInput(treeItem);



            parameters.add("root");

            /*treeItem = new TreeItem(tree, SWT.MULTI | SWT.CHECK | SWT.VIRTUAL |SWT.BORDER );
            treeItem.setText("(1)Test Session");
            treeItem.setImage(new Image(null, TreeViewer.class.getClassLoader().getResourceAsStream("icons/Folder-Main.JPG")));*/

            tree.addListener(SWT.Selection, new Listener() {
                public void handleEvent(Event e) {

                    if(e.item == null)
                    {
                        return;
                    }

                    treeSelection = tree.getSelection();    
                }
            });

            treeMenu.addListener(SWT.MouseDown, new Listener() {
                @Override
                public void handleEvent(Event event) {
                    tree.setSelection(new TreeItem[] {});
                    treeSelection = null;
                }
            });

            final Menu menu = new Menu(tree);
            tree.setMenu(menu);
            loadMenuDetails(menu);
        }

        public TreeItem getInput()
        {
            treeItem = new TreeItem(tree, SWT.MULTI | SWT.CHECK | SWT.VIRTUAL |SWT.BORDER );
            treeItem.setText("(1)Test Session");
            treeItem.setImage(new Image(null, TreeViewer.class.getClassLoader().getResourceAsStream("icons/Folder-Main.JPG")));

            return treeItem;

        }

        /**
         * This class provides the content for the tree in FileTree
         */

        class FileTreeContentProvider implements ITreeContentProvider {
          /**
           * Gets the children of the specified object
           * 
           * @param arg0
           *            the parent object
           * @return Object[]
           */
          public Object[] getChildren(Object arg0) {
            // Return the files and subdirectories in this directory
            //return ((File) arg0).listFiles();
              return null;
          }

          /**
           * Gets the parent of the specified object
           * 
           * @param arg0
           *            the object
           * @return Object
           */
          public Object getParent(Object arg0) {
            // Return this file's parent file
            //return ((File) arg0).getParentFile();
              return null;
          }

          /**
           * Returns whether the passed object has children
           * 
           * @param arg0
           *            the parent object
           * @return boolean
           */
          public boolean hasChildren(Object arg0) {
            // Get the children
            Object[] obj = getChildren(arg0);

            // Return whether the parent has children
            return obj == null ? false : obj.length > 0;
          }

      /**
       * Gets the root element(s) of the tree
       * 
       * @param arg0
       *            the input data
       * @return Object[]
       */
      /*public Object[] getElements(Object arg0) {
        // These are the root elements of the tree
        // We don't care what arg0 is, because we just want all
        // the root nodes in the file system
        return File.listRoots();
        //return "New ROOT";
      }*/

      public Object[] getElements(Object inputElement) {

            //TreeItem rootItem = new TreeItem((Tree) arg0, SWT.CHECK);
            //rootItem.setText("ROOT");
        //    return new Object[] { "Session Root" }; // your root item you want to display
          treeItem = new TreeItem(tree, SWT.MULTI | SWT.CHECK | SWT.VIRTUAL |SWT.BORDER );
            treeItem.setText("(1)Test Session");
            treeItem.setImage(new Image(null, TreeViewer.class.getClassLoader().getResourceAsStream("icons/Folder-Main.JPG")));
          if (inputElement instanceof TreeItem)
          {
              System.out.println("getelements");
              return ((List<String>)inputElement).toArray();
          }
            return new Object[] {parameters.toArray()};
        }

      /**
       * Disposes any created resources
       */
      public void dispose() {
        // Nothing to dispose
      }

      /**
       * Called when the input changes
       * 
       * @param arg0
       *            the viewer
       * @param arg1
       *            the old input
       * @param arg2
       *            the new input
       */
      public void inputChanged(Viewer arg0, Object arg1, Object arg2) {
        // Nothing to change
      }
    }

class FileTreeLabelProvider1 implements ILabelProvider {
      // The listeners
      private List listeners;

      // Images for tree nodes
      private Image file;

      private Image dir;

      // Label provider state: preserve case of file names/directories


      /**
       * Constructs a FileTreeLabelProvider
       */
      public FileTreeLabelProvider1() {
        // Create the list to hold the listeners
        listeners = new ArrayList();

        // Create the images
        try {
          file = new Image(null, new FileInputStream("images/file.gif"));
          dir = new Image(null, new FileInputStream("images/directory.gif"));
        } catch (FileNotFoundException e) {
          // Swallow it; we'll do without images
        }
      }



      /**
       * Gets the image to display for a node in the tree
       * 
       * @param arg0
       *            the node
       * @return Image
       */
      public Image getImage(Object arg0) {
        // If the node represents a directory, return the directory image.
        // Otherwise, return the file image.
        return ((File) arg0).isDirectory() ? dir : file;
      }

      /**
       * Gets the text to display for a node in the tree
       * 
       * @param arg0
       *            the node
       * @return String
       */
      public String getText(Object arg0) {
        // Get the name of the file
        String text = ((File) arg0).getName();

        // If name is blank, get the path
        if (text.length() == 0) {
          text = ((File) arg0).getPath();
        }

        // Check the case settings before returning the text
        return text ;
      }

      /**
       * Adds a listener to this label provider
       * 
       * @param arg0
       *            the listener
       */
      public void addListener(ILabelProviderListener arg0) {
        listeners.add(arg0);
      }

      /**
       * Called when this LabelProvider is being disposed
       */
      public void dispose() {
        // Dispose the images
        if (dir != null)
          dir.dispose();
        if (file != null)
          file.dispose();
      }

      /**
       * Returns whether changes to the specified property on the specified
       * element would affect the label for the element
       * 
       * @param arg0
       *            the element
       * @param arg1
       *            the property
       * @return boolean
       */
      public boolean isLabelProperty(Object arg0, String arg1) {
        return false;
      }

      /**
       * Removes the listener
       * 
       * @param arg0
       *            the listener to remove
       */
      public void removeListener(ILabelProviderListener arg0) {
        listeners.remove(arg0);
      }
    }

Answer 1

Try giving the tree object the parent composite and the flags (SWT.BORDER | SWT.CHECK) it worked for me this way

tree = new Tree(treeMenu, SWT.BORDER | SWT.CHECK);