이렇게 하니깐 되는군요
boolean needReturn = false;
int eventType;
try {
eventType = xpp.getEventType();
while(eventType != XmlPullParser.END_DOCUMENT){
if (eventType == XmlPullParser.START_TAG) {
if ("key".equals(xpp.getName())){
if (xpp.getAttributeValue(0).equals(key)) {
needReturn = true;
}
}
} else if (eventType == XmlPullParser.TEXT) {
if (needReturn) {
return xpp.getText();
}
}
eventType = xpp.next();
}
} catch (Exception e) {
e.printStackTrace();
}