Create A Field To Display A Parent And Child Relationship Between Items - Blackberry JAVA DEVELOPMENT ENVIRONMENT - - DEVELOPMENT GUIDE Manual

Development Guide
6. Create an instance of a ListCallback.
ListCallback myCallback = new ListCallback();
7. Set the call back of the ListField to be the ListCallback.
myList.setCallback(myCallback);
8. Use the ListCallBack object to add items to the ListField.
myCallback.add(myList, fieldOne);
myCallback.add(myList, fieldTwo);
9. Add the ListField to the MainScreen.
mainScreen.add(myList);

Create a field to display a parent and child relationship between items

A TreeField contains parent and child nodes.
1. Import the following classes:
• net.rim.device.api.ui.component.TreeField
• java.lang.String
• net.rim.device.api.ui.container.MainScreen
2. Import the net.rim.device.api.ui.component.TreeFieldCallback interface.
3. Implement the TreeFieldCallback interface.
4. Invoke TreeField.setExpanded() on the TreeField object to specify whether a folder is collapsible. In the
following code sample, we create a TreeField object and multiple child nodes to the TreeField object. We then
invoke TreeField.setExpanded() using node4 as a parameter to collapse the folder.
String fieldOne =
...
TreeCallback myCallback = new TreeCallback();
TreeField myTree = new TreeField(myCallback, Field.FOCUSABLE);
int node1 = myTree.addChildNode(0, fieldOne);
int node2 = myTree.addChildNode(0, fieldTwo);
int node3 = myTree.addChildNode(node2, fieldThree);
int node4 = myTree.addChildNode(node3, fieldFour);
...
int node10 = myTree.addChildNode(node1, fieldTen);
myTree.setExpanded(node4, false);
...
mainScreen.add(myTree);
22
new String("Main folder");
UI components