A DESCRIPTION OF THE PROBLEM :
jshell> String s = ""
s.conta + TAB - works
(s.conta + TAB - works
for (s.conta + TAB - works
if (s.conta + TAB - does not work
while (s.conta + TAB - does not work
jshell> String s = ""
s.conta + TAB - works
(s.conta + TAB - works
for (s.conta + TAB - works
if (s.conta + TAB - does not work
while (s.conta + TAB - does not work