Provide an assistive technology application with information about text changes

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Provide an assistive technology application with information about text changes

You can provide accessibility information about the custom UI controls that display text.

Import the required interfaces.
```
import net.rim.device.api.ui.accessibility.AccessibleContext;
import net.rim.device.api.ui.accessibility.AccessibleText;
```
AccessibleContext provides basic accessibility information about a custom UI control. AccessibleText provides information about the text in a custom UI control that displays text.

Create a class that extends Field and implements the AccessibleContext and AccessibleText interfaces.

public class AccessibleTextClass extends Field 
  implements AccessibleContext, AccessibleText 
{
}

Create variables to store the custom UI control's accessibility state and the contents.

private int _state;
private int _cursor, _anchor;
private String _text;
private Vector _lines; 
private Vector _words;

Implement AccessibleText.getAtIndex(int part, int index), to provide access to the text at a given position in the custom UI control.

public String getAtIndex(int part, int index)
{
  switch(part) 
  {
    case AccessibleText.CHAR:
      return String.valueOf(_text.charAt(index));
                
    case AccessibleText.LINE:
      return (String) _lines.elementAt(index);
                
    case AccessibleText.WORD:
      return (String) _words.elementAt(index);
  }
        
  return null;
}

Implement AccessibleText.getSelectionStart(), to provide access to the position of the first character of text that a BlackBerry® device user selects. Return 0 if the device user cannot select text in the custom UI control.
```
public int getSelectionStart() 
{
  return _anchor;
}
```
Implement AccessibleText.getSelectionEnd(), to provide access to the position of the last character of text that a BlackBerry device user selects. Return 0 if the device user cannot select text in the custom UI control.
```
public int getSelectionEnd() 
{
  return _cursor;
}
```
Implement AccessibleText.getCaretPosition(), to provide access to the position of the cursor within the text. Return 0 if the device user cannot select text in the custom UI control.
```
public int getCaretPosition() 
{
  return _cursor;
}
```

Implement AccessibleText.getSelectionText(), to provide access to the selected part of the text within the custom UI control.

public String getSelectionText() 
{
  int start = getSelectionStart();
  int end = getSelectionEnd();
  if (start<end) {
    return _text.getText(start,end);
  } else {
    return _text.getText(end,start);
  }
}

Implement AccessibleText.getLineCount(), to provide access to the number of lines of text within the custom UI control.
```
public int getLineCount()
{
  return _lines.size();
}
```
Implement AccessibleText.getCharCount(), to provide access to the number of characters in the text within the custom UI control.
```
public int getCharCount()
{
  return _text.length();
}
```

Parent topic: Accessibility

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Provide an assistive technology application with information about text changes