blackberry - ブラックベリーでツリービューの親アイテムと子アイテムをクリックして新しいクラスファイルを開く方法は?

Question

 public class Expandablelistview extends MainScreen {
    public Expandablelistview() {
    // A separator field between each type of control\
    // setTitle("Tree Field Demo");
    String parentfield1 = new String("Demo1");
    String parentfield2 = new String("Demo2");
    String childfield1 = new String("Demo3");
    String childfield2 = new String("Demo4");
    String parentfield3 = new String("Demo5");
    String parentfield4 = new String("Demo6");
    String childfield3 = new String("Demo7");
    String childfield4 = new String("Demo8");
    String childfield5 = new String("Demo9");
    String childfield6 = new String("Demo10");
    String parentfield5 = new String("Demo11");
    String childfield7 = new String("Demo12");
    String childfield8 = new String("Demo13");

    TreeCallback myCallback = new TreeCallback();
    final TreeField myTree = new TreeField(myCallback, Field.FOCUSABLE);
    myTree.setDefaultExpanded(false);

    int node12 = myTree.addChildNode(0, parentfield5);
    int node13 = myTree.addChildNode(node12, childfield7);
    int node14 = myTree.addChildNode(node12, childfield8);
    // int node7 = myTree.addChildNode(0, parentfield5);
    int node6 = myTree.addChildNode(0, parentfield4);
    int node11 = myTree.addChildNode(node6, childfield6);
    int node10 = myTree.addChildNode(node6, childfield5);
    int node8 = myTree.addChildNode(node6, childfield3);
    int node9 = myTree.addChildNode(node6, childfield4);
    int node5 = myTree.addChildNode(0, parentfield3);
    int node2 = myTree.addChildNode(0, parentfield2);
    int node3 = myTree.addChildNode(node2, childfield1);
    int node4 = myTree.addChildNode(node2, childfield2);
    int node1 = myTree.addChildNode(0, parentfield1);

    add(myTree);
    // myTree.setChangeListener(new myTreeChangeListener());

    // HERE I TRIED FOR ITEM CLICK


    FieldChangeListener fdbtncalculate = new FieldChangeListener() {

        public void fieldChanged(Field field, int context) {
            // TODO Auto-generated method stub
            int a = myTree.getNodeCount();
            System.out.print("mytree" + a);

            if (a == 0) {
                Dialog.alert("data");
            } else if (a == 1) {
                Dialog.alert("data");
            }


        }
    };
    myTree.setChangeListener(fdbtncalculate);

}

private class TreeCallback implements TreeFieldCallback {
    public void drawTreeItem(TreeField _tree, Graphics g, int node, int y,
            int width, int indent) {
        String text = (String) _tree.getCookie(node);
                    g.drawText(text, indent, y);

    }

}

}

私が間違っていることを知りたいですか？フィールドリスナーを使用するために、ツリービューの親アイテムと子アイテムのクリックでクラスファイルを開きたい