Error Saving a List in a xml File in Android -
i have implemented code capable of detecting ble signals , show them in listview (in each item of list show name, address , rssi) when try save xml file occurs error , stops app. here code:
package com.example.newblescan; import java.io.filenotfoundexception; import java.io.fileoutputstream; import java.io.ioexception; import java.io.objectoutputstream; import java.io.serializable; import com.example.newblescan.r; import android.app.activity; import android.app.listactivity; import android.bluetooth.bluetoothadapter; import android.bluetooth.bluetoothdevice; import android.bluetooth.bluetoothmanager; import android.content.context; import android.content.intent; import android.content.pm.packagemanager; import android.os.bundle; import android.view.menu; import android.view.menuitem; import android.view.view; import android.widget.listview; import android.widget.toast; import com.example.newblescan.adapter.bledevicesadapter; /** * activity scanning , displaying available bluetooth le devices. */ public class devicescanactivity extends listactivity { private static final int request_enable_bt = 1; private static final long scan_period = 500; private bledevicesadapter ledevicelistadapter; private bluetoothadapter bluetoothadapter; private scanner scanner; private save save; @override public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); getactionbar().settitle(r.string.title_devices); // use check determine whether ble supported on device. can // selectively disable ble-related features. if (!getpackagemanager().hassystemfeature(packagemanager.feature_bluetooth_le)) { toast.maketext(this, r.string.ble_not_supported, toast.length_short).show(); finish(); return; } // initializes bluetooth adapter. api level 18 , above, reference // bluetoothadapter through bluetoothmanager. final bluetoothmanager bluetoothmanager = (bluetoothmanager) getsystemservice(context.bluetooth_service); bluetoothadapter = bluetoothmanager.getadapter(); // checks if bluetooth supported on device. if (bluetoothadapter == null) { toast.maketext(this, r.string.error_bluetooth_not_supported, toast.length_short).show(); finish(); return; } } @override public boolean oncreateoptionsmenu(menu menu) { getmenuinflater().inflate(r.menu.gatt_scan, menu); if (scanner == null || !scanner.isscanning()) { menu.finditem(r.id.menu_stop).setvisible(false); menu.finditem(r.id.menu_scan).setvisible(true); menu.finditem(r.id.menu_refresh).setactionview(null); } else { menu.finditem(r.id.menu_stop).setvisible(true); menu.finditem(r.id.menu_scan).setvisible(false); menu.finditem(r.id.menu_refresh).setactionview( r.layout.actionbar_indeterminate_progress); } return true; } @override public boolean onoptionsitemselected(menuitem item) { switch (item.getitemid()) { case r.id.menu_scan: ledevicelistadapter.clear(); if (scanner == null) { scanner = new scanner(bluetoothadapter, mlescancallback); scanner.startscanning(); invalidateoptionsmenu(); } break; case r.id.menu_stop: if (scanner != null) { save = new save(ledevicelistadapter); scanner.stopscanning(); try { save.savedata(); } catch (filenotfoundexception e) { // todo auto-generated catch block e.printstacktrace(); } scanner = null; invalidateoptionsmenu(); } break; } return true; } @override protected void onresume() { super.onresume(); // ensures bluetooth enabled on device. if bluetooth not enabled, // fire intent display dialog asking user grant permission enable it. if (!bluetoothadapter.isenabled()) { final intent enablebtintent = new intent(bluetoothadapter.action_request_enable); startactivityforresult(enablebtintent, request_enable_bt); return; } init(); } @override protected void onactivityresult(int requestcode, int resultcode, intent data) { // user chose not enable bluetooth. if (requestcode == request_enable_bt) { if (resultcode == activity.result_canceled) { finish(); } else { init(); } } super.onactivityresult(requestcode, resultcode, data); } @override protected void onpause() { super.onpause(); if (scanner != null) { scanner.stopscanning(); scanner = null; } } @override protected void onlistitemclick(listview l, view v, int position, long id) { final bluetoothdevice device = ledevicelistadapter.getdevice(position); if (device == null) return; //final intent intent = new intent(this, deviceservicesactivity.class); //intent.putextra(deviceservicesactivity.extras_device_name, device.getname()); //intent.putextra(deviceservicesactivity.extras_device_address, device.getaddress()); //startactivity(intent); } private void init() { if (ledevicelistadapter == null) { ledevicelistadapter = new bledevicesadapter(getbasecontext()); setlistadapter(ledevicelistadapter); } if (scanner == null) { scanner = new scanner(bluetoothadapter, mlescancallback); scanner.startscanning(); } invalidateoptionsmenu(); } // device scan callback. private bluetoothadapter.lescancallback mlescancallback = new bluetoothadapter.lescancallback() { @override public void onlescan(final bluetoothdevice device, final int rssi, byte[] scanrecord) { runonuithread(new runnable() { @override public void run() { ledevicelistadapter.adddevice(device, rssi); ledevicelistadapter.notifydatasetchanged(); } }); } }; private static class scanner extends thread { private final bluetoothadapter bluetoothadapter; private final bluetoothadapter.lescancallback mlescancallback; private volatile boolean isscanning = false; scanner(bluetoothadapter adapter, bluetoothadapter.lescancallback callback) { bluetoothadapter = adapter; mlescancallback = callback; } public boolean isscanning() { return isscanning; } public void startscanning() { synchronized (this) { isscanning = true; start(); } } public void stopscanning() { synchronized (this) { isscanning = false; bluetoothadapter.stoplescan(mlescancallback); } } @override public void run() { try { while (true) { synchronized (this) { if (!isscanning) break; bluetoothadapter.startlescan(mlescancallback); } sleep(scan_period); synchronized (this) { bluetoothadapter.stoplescan(mlescancallback); } } } catch (interruptedexception ignore) { } { bluetoothadapter.stoplescan(mlescancallback); } } } public class save implements serializable { /** * */ private bledevicesadapter ledevicelistadapter; private static final long serialversionuid = 1l; save(bledevicesadapter blelist) { ledevicelistadapter = blelist; } public void savedata() throws filenotfoundexception{ string filename = "file.txt"; fileoutputstream fos = null; //bundle extras = getintent().getextras(); //long timestamp = extras.getlong("currenttime"); try { fos= openfileoutput(filename, context.mode_private); objectoutputstream out = new objectoutputstream(fos); //out.write((int) timestamp); out.writeobject(ledevicelistadapter); out.close(); toast.maketext(devicescanactivity.this, r.string.list_saved, toast.length_short).show(); } catch (filenotfoundexception e){ e.printstacktrace(); } catch (ioexception e){ e.printstacktrace(); } } } } in here when press button, in r.id.menu_stop case, calls class save save list xml file. here logcat when execute app:
new logcat!!!!!:
03-10 10:33:02.426: d/bluetoothadapter(21891): startlescan(): null 03-10 10:33:02.431: d/bluetoothadapter(21891): onclientregistered() - status=0 clientif=4 03-10 10:33:02.441: d/abslistview(21891): unregisterirlistener() called 03-10 10:33:02.466: d/abslistview(21891): unregisterirlistener() called 03-10 10:33:02.486: d/bluetoothadapter(21891): stoplescan() 03-10 10:33:02.521: w/system.err(21891): java.io.notserializableexception: com.example.newblescan.adapter.bledevicesadapter 03-10 10:33:02.521: w/system.err(21891): @ java.io.objectoutputstream.writenewobject(objectoutputstream.java:1364) 03-10 10:33:02.521: w/system.err(21891): @ java.io.objectoutputstream.writeobjectinternal(objectoutputstream.java:1671) 03-10 10:33:02.521: w/system.err(21891): @ java.io.objectoutputstream.writeobject(objectoutputstream.java:1517) 03-10 10:33:02.521: w/system.err(21891): @ java.io.objectoutputstream.writeobject(objectoutputstream.java:1481) 03-10 10:33:02.521: w/system.err(21891): @ com.example.newblescan.devicescanactivity$save.savedata(devicescanactivity.java:295) 03-10 10:33:02.521: w/system.err(21891): @ com.example.newblescan.devicescanactivity.onoptionsitemselected(devicescanactivity.java:116) 03-10 10:33:02.521: w/system.err(21891): @ android.app.activity.onmenuitemselected(activity.java:2640) 03-10 10:33:02.521: w/system.err(21891): @ com.android.internal.policy.impl.phonewindow.onmenuitemselected(phonewindow.java:1171) 03-10 10:33:02.521: w/system.err(21891): @ com.android.internal.view.menu.menubuilder.dispatchmenuitemselected(menubuilder.java:735) 03-10 10:33:02.521: w/system.err(21891): @ com.android.internal.view.menu.menuitemimpl.invoke(menuitemimpl.java:152) 03-10 10:33:02.526: w/system.err(21891): @ com.android.internal.view.menu.menubuilder.performitemaction(menubuilder.java:874) 03-10 10:33:02.526: w/system.err(21891): @ com.android.internal.view.menu.actionmenuview.invokeitem(actionmenuview.java:630) 03-10 10:33:02.526: w/system.err(21891): @ com.android.internal.view.menu.actionmenuitemview.onclick(actionmenuitemview.java:200) 03-10 10:33:02.526: w/system.err(21891): @ android.view.view.performclick(view.java:4475) 03-10 10:33:02.526: w/system.err(21891): @ android.view.view$performclick.run(view.java:18786) 03-10 10:33:02.526: w/system.err(21891): @ android.os.handler.handlecallback(handler.java:730) 03-10 10:33:02.526: w/system.err(21891): @ android.os.handler.dispatchmessage(handler.java:92) 03-10 10:33:02.526: w/system.err(21891): @ android.os.looper.loop(looper.java:137) 03-10 10:33:02.526: w/system.err(21891): @ android.app.activitythread.main(activitythread.java:5493) 03-10 10:33:02.526: w/system.err(21891): @ java.lang.reflect.method.invokenative(native method) 03-10 10:33:02.526: w/system.err(21891): @ java.lang.reflect.method.invoke(method.java:525) 03-10 10:33:02.526: w/system.err(21891): @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1209) 03-10 10:33:02.526: w/system.err(21891): @ com.android.internal.os.zygoteinit.main(zygoteinit.java:1025) 03-10 10:33:02.531: w/system.err(21891): @ dalvik.system.nativestart.main(native method) 03-10 10:33:02.931: d/bluetoothadapter(21891): stoplescan() 03-10 10:33:02.931: d/bluetoothadapter(21891): stoplescan() 03-10 10:33:07.701: d/abslistview(21891): unregisterirlistener() called 03-10 10:33:07.911: d/abslistview(21891): ondetachedfromwindow can solve error or put correction of code ot code might missing?? pleaseee help!!!!!!!
update: when press button stop scan, stops don´t know why doesn´t save or create xml file. also, doesn´t pop toast knowing has been saved. updated code above , logcat. can solve new problems??!!!!!!
in savedata()
toast.maketext(null, r.string.list_saved, toast.length_short).show(); passing null in context ! ?
that should be,
toast.maketext(devicescanactivity.this, r.string.list_saved, toast.length_short).show(); also, initialise fileoutputstream variable,
fileoutputstream fos = null; instead of
fileoutputstream fos;
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