Provide an assistive technology application with information about a UI change

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Provide an assistive technology application with information about a UI change

Import the required interface.

import net.rim.device.api.ui.accessibility.AccessibleContext;

Implement AccessibleContext to represent the information about changes to a custom UI component that an application can make available.
Create variables to store the accessibility information for a custom UI component, such as state information.
```
private int _state = AccessibleState.UNSET;
private String _accessibleName;
private String _title;
```

Create the methods that add and remove the states for a custom UI component.

protected void addAccessibleStates(int states) 
{
  _state = _state & ~AccessibleState.UNSET;
  _state = _state | states;
}

protected void removeAccessibleStates(int states) 
{
  _state = _state & ~states;
}

public void setAccessibleName(String accessibleName) 
{
  _accessibleName = accessibleName;
}

Implement the get() methods of AccessibleContext, to allow access to tabular, textual, or numerical information for a custom UI component. Return null if the method does not apply to a custom UI control. For example, if the control does not provide textual information, return null in getAccessibleText().
```
public AccessibleTable getAccessibleTable() 
{
  return null;
}

public AccessibleText getAccessibleText() 
{
  return null;
}

public AccessibleValue getAccessibleValue() 
{
  return null;
}
```
Create a method that returns an instance of the class that implements AccessibleContext, to provide information about a change to a custom UI component.
```
public AccessibleContext getAccessibleContext() 
{
  return this;
}
```
Implement AccessibleContext.getAccessibleRole(), to provide information about the type of custom UI control.
```
public int getAccessibleRole() 
{
  return AccessibleRole.PANEL;
}
```
Implement AccessibleContext.getAccessibleChildCount(), to provide information about the number of accessible child components that a custom UI component contains. It is up to you as the developer of a custom UI component to decide whether or not it contains accessible children. One criterion you can use to decide whether a child element is an accessible child component is whether a child element can gain focus and whether the user can interact with the child element independently.
```
public int getAccessibleChildCount() 
{
  return _icons.size();
}
```
Implement AccessibleContext.getAccessibleChildAt(int), to provide information about an accessible child component that a custom UI component contains.
```
public AccessibleContext getAccessibleChildAt(int arg0) 
{
  return (Icon) _icons.elementAt( index );
}
```
Implement AccessibleContext.getAccessibleName(), to provide the name of a custom UI component that changes.
```
public String getAccessibleName() 
{
  return _accessibleName;
}
```
Create a method that invokes AccessibleEventDispatcher.dispatchAccessibleEvent(stateChange, oldState, newState, this), to send a notification when the state of a custom UI component changes. Use the following information as arguments to the method:
- the event
- the old state of the custom UI component
- the new state of the custom UI component
- an instance of the custom UI component
```
protected void onFocus(int direction)
{
  super.onFocus(direction);
       
  int oldState = _state;
  _state = _state | AccessibleState.FOCUSED;
     
  if(isVisible())
  {
    AccessibleEventDispatcher.dispatchAccessibleEvent( 
      AccessibleContext.ACCESSIBLE_STATE_CHANGED, 
      new Integer(oldState), 
      new Integer(_state), 
      this);
  }
}
```

Parent topic: Accessibility

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Provide an assistive technology application with information about a UI change