this class should allow me connect url , retrieve data from. converts json data in string. maybe there problem here , can't see it. im pretty new sort of programming.
public class networkconnection extends asynctask<string, void, string> { private static final string debug_tag = "httpexample"; protected string doinbackground(string... urls) { try{ return downloadurl(urls[0]); } catch (ioexception e) { return "unable retrieve web page"; } } //fetch data url public string downloadurl(string myurl) throws ioexception { inputstream = null; int len = 500; string text = new string(); try { url url = new url(myurl); httpurlconnection conn = (httpurlconnection) url.openconnection(); conn.setreadtimeout(10000 /* milliseconds */); conn.setconnecttimeout(15000 /* milliseconds */); conn.setrequestmethod("get"); conn.setdoinput(true); // starts query conn.connect(); int response = conn.getresponsecode(); log.d(debug_tag, "the response is: " + response); = conn.getinputstream(); try { bufferedreader br = new bufferedreader( new inputstreamreader( conn.getinputstream())); stringbuilder sb = new stringbuilder(); string line; while ((line = br.readline()) != null) { sb.append(line + "\n"); } br.close(); jsonarray data = new jsonarray(sb.tostring()); (int = 0; < data.length(); i++) { jsonobject row = data.getjsonobject(i); string klasse = row.getstring("k_nr"); string raum = row.getstring("k_raum"); text = text + klasse + ": " + raum + "\n"; } } catch (ioexception e) { } catch (jsonexception e) { e.printstacktrace(); } } { if (is != null) { is.close(); } } return text; } @override protected void onpostexecute(string s){ super.onpostexecute(s); } }
this class in main thread ui is. here try access url class networkconnection. problem don't know how thread correctly.
public class start extends activity { // public string url = new string("http://10.0.2.2/?action=getklassen"); // public string url = new string("http://127.0.0.1/webservice/ajax.php?action=getklassen"); public string url; networkconnection netcon; public textview testausgabe; @override public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.main); intent = getintent(); string val = i.getstringextra("klasse"); textview ausgabe = (textview) findviewbyid(r.id.ausgabe); testausgabe = (textview)findviewbyid(r.id.testausgabe); netcon = new networkconnection(); url = new string("http://10.0.2.2/?action=getklassen"); ausgabe.settext(val); } public void myclickhandler(view view) { connectivitymanager connmgr = (connectivitymanager) getsystemservice(context.connectivity_service); networkinfo networkinfo = connmgr.getactivenetworkinfo(); if (networkinfo != null && networkinfo.isconnected()) { new networkconnection().execute(url); } else { testausgabe.settext("no network connection available."); } } public void onclick(view view){ } public void zeigeliste_click (view view) { startactivity(new intent(this, klassenview.class)); } public void ladedaten_click(view view) { string data; data = netcon.doinbackground(url); testausgabe.settext(data); } }
here have exception thrown. when click on button should load data app crashes. has threading problem don't understand other exceptions. if great. in advance.
01-29 11:10:38.776 6648-6648/com.example.httptest e/androidruntime: fatal exception: main process: com.example.httptest, pid: 6648 java.lang.illegalstateexception: not execute method android:onclick @ android.view.view$declaredonclicklistener.onclick(view.java:4452) @ android.view.view.performclick(view.java:5198) @ android.view.view$performclick.run(view.java:21147) @ android.os.handler.handlecallback(handler.java:739) @ android.os.handler.dispatchmessage(handler.java:95) @ android.os.looper.loop(looper.java:148) @ android.app.activitythread.main(activitythread.java:5417) @ java.lang.reflect.method.invoke(native method) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:726) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:616) caused by: java.lang.reflect.invocationtargetexception @ java.lang.reflect.method.invoke(native method) @ android.view.view$declaredonclicklistener.onclick(view.java:4447) @ android.view.view.performclick(view.java:5198) @ android.view.view$performclick.run(view.java:21147) @ android.os.handler.handlecallback(handler.java:739) @ android.os.handler.dispatchmessage(handler.java:95) @ android.os.looper.loop(looper.java:148) @ android.app.activitythread.main(activitythread.java:5417) @ java.lang.reflect.method.invoke(native method) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:726) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:616) caused by: android.os.networkonmainthreadexception @ android.os.strictmode$androidblockguardpolicy.onnetwork(strictmode.java:1273) @ libcore.io.blockguardos.connect(blockguardos.java:110) @ libcore.io.iobridge.connecterrno(iobridge.java:154) @ libcore.io.iobridge.connect(iobridge.java:122) @ java.net.plainsocketimpl.connect(plainsocketimpl.java:183) @ java.net.plainsocketimpl.connect(plainsocketimpl.java:452) @ java.net.socket.connect(socket.java:884) @ com.android.okhttp.internal.platform.connectsocket(platform.java:117) @ com.android.okhttp.internal.http.socketconnector.connectrawsocket(socketconnector.java:160) @ com.android.okhttp.internal.http.socketconnector.connectcleartext(socketconnector.java:67) @ com.android.okhttp.connection.connect(connection.java:152) @ com.android.okhttp.connection.connectandsetowner(connection.java:185) @ com.android.okhttp.okhttpclient$1.connectandsetowner(okhttpclient.java:128) @ com.android.okhttp.internal.http.httpengine.nextconnection(httpengine.java:341) @ com.android.okhttp.internal.http.httpengine.connect(httpengine.java:330) @ com.android.okhttp.internal.http.httpengine.sendrequest(httpengine.java:248) @ com.android.okhttp.internal.huc.httpurlconnectionimpl.execute(httpurlconnectionimpl.java:433) @ com.android.okhttp.internal.huc.httpurlconnectionimpl.connect(httpurlconnectionimpl.java:114) @ com.example.httptest.networkconnection.downloadurl(networkconnection.java:50) @ com.example.httptest.networkconnection.doinbackground(networkconnection.java:29) @ com.example.httptest.start.ladedaten_click(start.java:62) @ java.lang.reflect.method.invoke(native method) @ android.view.view$declaredonclicklistener.onclick(view.java:4447) @ android.view.view.performclick(view.java:5198) @ android.view.view$performclick.run(view.java:21147) @ android.os.handler.handlecallback(handler.java:739) @ android.os.handler.dispatchmessage(handler.java:95) @ android.os.looper.loop(looper.java:148) @ android.app.activitythread.main(activitythread.java:5417) @ java.lang.reflect.method.invoke(native method) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:726) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:616)
actually! made mistake in code. have use
netcon.execute(url); instead of netcon.doinbackground(url); , once execute() method called , clicked again start method before completing previous doinbackground() , exception occur again. 1 thing: inside method onpreexecute(), prevent button clicked again , onpostexecute(), make clickable again.
so doing way preventing create new thread. cheers!
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