java - URLConnection receive wrong text from php server -

i have app has 4 activities.in first activity want request text website (php file). first time press button data works fine in next times press button, returns correct text concatenates previous text.see example:

first press: returns: "abc" second press: returns: "abcabc" (must return abc) third press: returns: "abcabcabc" (must return abc) . 

1. i clear text view each time.
2. i close connection each time.
3. i close bufferedreader each time.
4. i close.

activity1:

try{     url u = new url(uu);     httpurlconnection con = (httpurlconnection) u.openconnection(proxy.no_proxy);     con.setdooutput(true);     con.setusecaches(false);     printstream pr = new printstream(con.getoutputstream());     pr.print("code=3&arg1=" + str);     bufferedreader br = new bufferedreader(new inputstreamreader(con.getinputstream(),"utf-8"));     string l;     while ((l=br.readline())!=null){         z = z + "\n" + l;     }     br.close();     pr.close();     con.disconnect();     runonuithread(new runnable() {         @override         public void run() {             textview tx = (textview) findviewbyid(r.id.textview2);             tx.setmovementmethod(new scrollingmovementmethod());             tx.settext("");             tx.settext(z);         }     }); } catch (final exception ex){ } 

i don't see declared z string, appending it.

you should either clear it, or use new string each request.

and use stringbuilder. memory usage lower.