how can i replace some specif text in GWT TextArea -

how can i replace some specif text in GWT TextArea -

i trying replace specific word or @ specific index(whichever easier) . new word.

i not able find solution entering text within textarea @ specific index .

is there anyway

thanks

for illustration . in textarea text : "hello, testing" want insert testing12 instead of testing .

thanks

something this:

mytextarea.setvalue(mytextarea.getvalue().replace(mytextarea.getselectedtext(), "new text"));

gwt