php - Error, my app stops each time it transfers data from the app to the database or vice versa -
here of code. error in logcat. in advance.
error: caused by: java.lang.nullpointerexception: attempt invoke virtual method 'java.lang.string.org.json.jsonobject.tostring()' on null object reference
login.java
public class login extends activity implements onclicklistener { private edittext user, pass; private button msubmit, mregister; private progressdialog pdialog; jsonparser jsonparser = new jsonparser(); private static final string tag_success = "success"; private static final string tag_message = "message"; @override protected void oncreate(bundle savedinstancestate) { // todo auto-generated method stub super.oncreate(savedinstancestate); setcontentview(r.layout.login); // setup input fields user = (edittext) findviewbyid(r.id.username); pass = (edittext) findviewbyid(r.id.password); // setup buttons msubmit = (button) findviewbyid(r.id.login); mregister = (button) findviewbyid(r.id.register); // register listeners msubmit.setonclicklistener(this); mregister.setonclicklistener(this); } @override public void onclick(view v) { int id = v.getid(); if (id == r.id.login) { new attemptlogin().execute(); } else if (id == r.id.register) { intent = new intent(this, register.class); startactivity(i); } else { } } class attemptlogin extends asynctask<string, string, string> { boolean failure = false; @override protected void onpreexecute() { super.onpreexecute(); pdialog = new progressdialog(login.this); pdialog.setmessage("attempting login..."); pdialog.setindeterminate(false); pdialog.setcancelable(true); pdialog.show(); } @override protected string doinbackground(string... args) { int success; string username = user.gettext().tostring(); string password = pass.gettext().tostring(); try { list<namevaluepair> params = new arraylist<namevaluepair>(); params.add(new basicnamevaluepair("username", username)); params.add(new basicnamevaluepair("password", password)); log.d("request!", "starting"); jsonobject json = jsonparser.makehttprequest(login_url, "post", params); log.d("login attempt", json.tostring()); success = json.getint(tag_success); if (success == 1) { log.d("login successful!", json.tostring()); sharedpreferences sp = preferencemanager .getdefaultsharedpreferences(login.this); editor edit = sp.edit(); edit.putstring("username", username); edit.commit(); intent = new intent(login.this, readcomments.class); finish(); startactivity(i); return json.getstring(tag_message); } else { log.d("login failure!", json.getstring(tag_message)); return json.getstring(tag_message); } } catch (jsonexception e) { e.printstacktrace(); } return null; } protected void onpostexecute(string file_url) { pdialog.dismiss(); if (file_url != null) { toast.maketext(login.this, file_url, toast.length_long).show(); } } } }
register.java
public class register extends activity implements onclicklistener{ private edittext user, pass; private button mregister; private progressdialog pdialog; jsonparser jsonparser = new jsonparser(); private static final string tag_success = "success"; private static final string tag_message = "message"; @override protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.register); user = (edittext)findviewbyid(r.id.username); pass = (edittext)findviewbyid(r.id.password); mregister = (button)findviewbyid(r.id.register); mregister.setonclicklistener(this); } @override public void onclick(view v) { new createuser().execute(); } class createuser extends asynctask<string, string, string> { @override protected void onpreexecute() { super.onpreexecute(); pdialog = new progressdialog(register.this); pdialog.setmessage("creating user..."); pdialog.setindeterminate(false); pdialog.setcancelable(true); pdialog.show(); } @override protected string doinbackground(string... args) { int success; string username = user.gettext().tostring(); string password = pass.gettext().tostring(); try { list<namevaluepair> params = new arraylist<namevaluepair>(); params.add(new basicnamevaluepair("username", username)); params.add(new basicnamevaluepair("password", password)); log.d("request!", "starting"); jsonobject json = jsonparser.makehttprequest( register_url, "post", params); log.d("registering attempt", json.tostring()); success = json.getint(tag_success); if (success == 1) { log.d("user created!", json.tostring()); finish(); return json.getstring(tag_message); }else{ log.d("registering failure!", json.getstring(tag_message)); return json.getstring(tag_message); } } catch (jsonexception e) { e.printstacktrace(); } return null; } protected void onpostexecute(string file_url) { // dismiss dialog once product deleted pdialog.dismiss(); if (file_url != null){ toast.maketext(register.this, file_url, toast.length_long).show(); } } } }
jsonparser.java
public class jsonparser { static inputstream = null; static jsonobject jobj = null; static string json = ""; public jsonparser() { } public jsonobject getjsonfromurl(final string url) { try { defaulthttpclient httpclient = new defaulthttpclient(); httppost httppost = new httppost(url); httpresponse httpresponse = httpclient.execute(httppost); httpentity httpentity = httpresponse.getentity(); = httpentity.getcontent(); } catch (unsupportedencodingexception e) { e.printstacktrace(); } catch (clientprotocolexception e) { e.printstacktrace(); } catch (ioexception e) { e.printstacktrace(); } try { bufferedreader reader = new bufferedreader(new inputstreamreader( is, "iso-8859-1"), 8); stringbuilder sb = new stringbuilder(); string line = null; while ((line = reader.readline()) != null) { sb.append(line + "\n"); } is.close(); json = sb.tostring(); } catch (exception e) { log.e("buffer error", "error converting result " + e.tostring()); log.e("log_tag", "failed data was:\n" + json); } try { jobj = new jsonobject(json); } catch (jsonexception e) { log.e("json parser", "error parsing data " + e.tostring()); log.e("log_tag", "failed data was:\n" + json); } return jobj; } public jsonobject makehttprequest(string url, string method, list<namevaluepair> params) { try { if(method == "post"){ defaulthttpclient httpclient = new defaulthttpclient(); httppost httppost = new httppost(url); httppost.setentity(new urlencodedformentity(params)); httpresponse httpresponse = httpclient.execute(httppost); httpentity httpentity = httpresponse.getentity(); = httpentity.getcontent(); }else if(method == "get"){ defaulthttpclient httpclient = new defaulthttpclient(); string paramstring = urlencodedutils.format(params, "utf-8"); url += "?" + paramstring; httpget httpget = new httpget(url); httpresponse httpresponse = httpclient.execute(httpget); httpentity httpentity = httpresponse.getentity(); = httpentity.getcontent(); } } catch (unsupportedencodingexception e) { e.printstacktrace(); } catch (clientprotocolexception e) { e.printstacktrace(); } catch (ioexception e) { e.printstacktrace(); } try { bufferedreader reader = new bufferedreader(new inputstreamreader( is, "iso-8859-1"), 8); stringbuilder sb = new stringbuilder(); string line = null; while ((line = reader.readline()) != null) { sb.append(line + "\n"); } is.close(); json = sb.tostring(); } catch (exception e) { log.e("buffer error", "error converting result " + e.tostring()); log.e("log_tag", "failed data was:\n" + json); } try { jobj = new jsonobject(json); } catch (jsonexception e) { log.e("json parser", "error parsing data " + e.tostring()); log.e("log_tag", "failed data was:\n" + json); } return jobj; } }
login.php
<?php require("config.inc.php"); if (!empty($_post)) { $query = " select id, username, password users username = :username "; $query_params = array( ':username' => $_post['username'] ); try { $stmt = $db->prepare($query); $result = $stmt->execute($query_params); } catch (pdoexception $ex) { $response["success"] = 0; $response["message"] = "database error1. please try again!"; die(json_encode($response)); } $validated_info = false; $row = $stmt->fetch(); if ($row) { if ($_post['password'] === $row['password']) { $login_ok = true; } } if ($login_ok) { $response["success"] = 1; $response["message"] = "login successful!"; die(json_encode($response)); } else { $response["success"] = 0; $response["message"] = "invalid credentials!"; die(json_encode($response)); } } else { ?> <h1>login</h1> <form action="login.php" method="post"> username:<br /> <input type="text" name="username" placeholder="username" /> <br /><br /> password:<br /> <input type="password" name="password" placeholder="password" value="" /> <br /><br /> <input type="submit" value="login" /> </form> <a href="register.php">register</a> <?php } ?> register.php
require("config.inc.php"); if (!empty($_post)) { if (empty($_post['username']) || empty($_post['password'])) { $response["success"] = 0; $response["message"] = "please enter both username , password."; die(json_encode($response)); } $query = " select 1 users username = :user"; $query_params = array( ':user' => $_post['username'] ); try { $stmt = $db->prepare($query); $result = $stmt->execute($query_params); } catch (pdoexception $ex) { $response["success"] = 0; $response["message"] = "database error1. please try again!"; die(json_encode($response)); } $row = $stmt->fetch(); if ($row) { $response["success"] = 0; $response["message"] = "i'm sorry, username in use"; die(json_encode($response)); } $query = "insert users ( username, password ) values ( :user, :pass ) "; $query_params = array( ':user' => $_post['username'], ':pass' => $_post['password'] ); try { $stmt = $db->prepare($query); $result = $stmt->execute($query_params); } catch (pdoexception $ex) { $response["success"] = 0; $response["message"] = "database error2. please try again!"; die(json_encode($response)); } $response["success"] = 1; $response["message"] = "username added!"; echo json_encode($response); } else { ?> <h1>register</h1> <form action="register.php" method="post"> username:<br /> <input type="text" name="username" value="" /> <br /><br /> password:<br /> <input type="password" name="password" value="" /> <br /><br /> <input type="submit" value="register new user" /> </form> <?php } ?>
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