java - Same serial port code is functioning differently in different activites -

so i'm writing app reads reads in data serial port. data coming in arduino connected force transducer - essentially, app meant measure weight of something. found serial port code here: https://www.allaboutcircuits.com/projects/communicate-with-your-arduino-through-android/, , i'm using in multiple different activities (since need activity calibration, activity actual measuring, etc.). problem same exact serial port code working in 1 activity , not working in another. works in activity, example:

public class enterdataactivity extends appcompatactivity { private static final long timer_delay = 5000; private static final long timer_length = 15000; edittext entermax, entermin; button submitmax, submitmin, continuebutton; chronometer emptybagtimer; boolean firstmeasure, getemptybagdata, canentermax, canentermin; arraylist<string> emptybagdata; float maxload, minload;  // serial port variables: public final string action_usb_permission = "com.example.jake.usb_permission"; usbmanager usbmanager; usbdevice device; usbserialdevice serialport; usbdeviceconnection connection;  usbserialinterface.usbreadcallback mcallback = new usbserialinterface.usbreadcallback() { //defining callback triggers whenever data read.     @override     public void onreceiveddata(byte[] arg0) {         string data;         try {             data = new string(arg0, "utf-8");             if(getemptybagdata)                 emptybagdata.add(data);         } catch (unsupportedencodingexception e) {}     } }; private final broadcastreceiver broadcastreceiver = new broadcastreceiver() { //broadcast receiver automatically start , stop serial connection.     @override     public void onreceive(context context, intent intent) {         if (intent.getaction().equals(action_usb_permission)) {             boolean granted = intent.getextras().getboolean(usbmanager.extra_permission_granted);             if (granted) {                 connection = usbmanager.opendevice(device);                 serialport = usbserialdevice.createusbserialdevice(device, connection);                 if (serialport != null) {                     if (serialport.open()) { //set serial connection parameters.                         serialport.setbaudrate(9600);                         serialport.setdatabits(usbserialinterface.data_bits_8);                         serialport.setstopbits(usbserialinterface.stop_bits_1);                         serialport.setparity(usbserialinterface.parity_none);                         serialport.setflowcontrol(usbserialinterface.flow_control_off);                         serialport.read(mcallback);                     } else {                         log.d("serial", "port not open");                     }                 } else {                     log.d("serial", "port null");                 }             } else {                 log.d("serial", "perm not granted");             }         } else if (intent.getaction().equals(usbmanager.action_usb_device_attached)) {             start();         } else if (intent.getaction().equals(usbmanager.action_usb_device_detached)) {             stop();         }     } };  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_enter_data);     usbmanager = (usbmanager) getsystemservice(usb_service);     intentfilter filter = new intentfilter();     filter.addaction(action_usb_permission);     filter.addaction(usbmanager.action_usb_device_attached);     filter.addaction(usbmanager.action_usb_device_detached);     registerreceiver(broadcastreceiver, filter);      entermax = (edittext) findviewbyid(r.id.entermax);     entermin = (edittext) findviewbyid(r.id.entermin);     submitmax = (button) findviewbyid(r.id.submitmax);     submitmin = (button) findviewbyid(r.id.submitmin);     continuebutton = (button) findviewbyid(r.id.continuebutton);     emptybagtimer = (chronometer) findviewbyid(r.id.emptybagtimer);      firstmeasure = true;     getemptybagdata = false;     canentermax = true;     canentermin = true;      emptybagdata = new arraylist<>();      start(); }  // method: measureemptybag // description: method called when button measure mass of empty bag // pressed. starts chronometer , serial port, first waiting timer_delay milliseconds // button press, sets boolean true causes serial data added // arraylist on next timer_length milliseconds. sets next views in // enter data process visible. firstmeasure boolean prevent spamming. public void measureemptybag(view view){     if(firstmeasure) {         firstmeasure = false;         start();         emptybagtimer.setbase(systemclock.elapsedrealtime());         emptybagtimer.start();         emptybagtimer.setformat("waiting - %s");         emptybagtimer.setonchronometerticklistener(new chronometer.onchronometerticklistener() {             @override             public void onchronometertick(chronometer chronometer) {                 if (systemclock.elapsedrealtime() - emptybagtimer.getbase() <= timer_delay)                     emptybagtimer.setformat("waiting - %s");                 else if (systemclock.elapsedrealtime() - emptybagtimer.getbase() <= timer_delay + timer_length) {                     emptybagtimer.setformat("calculating - %s");                     getemptybagdata = true;                 }                 else if (systemclock.elapsedrealtime() - emptybagtimer.getbase() > timer_delay + timer_length) {                     getemptybagdata = false;                     emptybagtimer.stop();                     entermax.setvisibility(view.visible);                     submitmax.setvisibility(view.visible);                 }                 else                     emptybagtimer.setformat("waiting - %s");             }         });     } }  // method: setmaxload // description: called when submit button pressed max load, method trys // pull max load value edit text , store it. if successful (the user has // entered in number) sets next views in enter data process visible. public void setmaxload(view view){     if(canentermax){         try {             canentermax = false;             maxload = float.parsefloat(entermax.gettext().tostring());             entermin.setvisibility(view.visible);             submitmin.setvisibility(view.visible);         } catch (exception e) {} // in case user enters non number     } }  // method: setminload // description: called when submit button pressed min load, method trys // pull min load value edit text , store it. if successful (the user has // entered in number) sets next view in enter data process visible. public void setminload(view view){     if(canentermin){         try {             canentermin = false;             minload = float.parsefloat(entermin.gettext().tostring());             continuebutton.setvisibility(view.visible);         } catch (exception e) {} // in case user enters non number     } }  // method: continuepressed // description: method called when continue button pressed. averages of // data read in on measure empty mass period find mass when empty, writes // value along maxload , minload file later use. starts pump // activity public void continuepressed(view view){     int emptymasssum = 0;     int emptymass;      // cleaning emptybagdata include 3,2, or 1 digit numbers (the serial output gets     // wonky , spits out weird numbers throw off calculations below,     // numbers need removed)     (int = emptybagdata.size() - 1; >= 0; i--)         if (emptybagdata.get(i).length() != 3)             emptybagdata.remove(i);      // add values in emptybagdata (try catch in case non-number read in)     (int = emptybagdata.size() - 1; >= 0; i--) {         try {             emptymasssum += integer.parseint(emptybagdata.get(i));         } catch (exception e) {             emptybagdata.remove(i);         }     }      emptymass = emptymasssum / emptybagdata.size();      fileoutputstream outputstream;      string dataout = "e" + emptymass + "mx" + maxload + "mn" + minload + ";";      try {         outputstream = openfileoutput("bagdata.txt", context.mode_private);         outputstream.write(dataout.getbytes());         outputstream.close();     } catch (exception e) {         continuebutton.settext(r.string.file_write_error_message);     }      intent intent = new intent(this, pumpactivity.class);     startactivity(intent); }  // serial port methods: public void start() {     hashmap<string, usbdevice> usbdevices = usbmanager.getdevicelist();     if (!usbdevices.isempty()) {         boolean keep = true;         (map.entry<string, usbdevice> entry : usbdevices.entryset()) {             device = entry.getvalue();             int devicevid = device.getvendorid();             if (devicevid == 10755 || devicevid == 9025)//arduino vendor id             {                 pendingintent pi = pendingintent.getbroadcast(this, 0, new intent(action_usb_permission), 0);                 usbmanager.requestpermission(device, pi);                 keep = false;             } else {                 connection = null;                 device = null;             }              if (!keep)                 break;         }     } }  public void stop() {     if(serialport!=null)         serialport.close(); } } 

by "it works", mean can data coming in serial port , use it. however, same code not work here:

public class pumpactivity extends appcompatactivity { file calibrationdata, bagdata; int mass1, mass2, read1, read2, emptymassnum; float maxload, minload; double slope, currentmassval, emptymass; boolean status, runtimer; textview statustextview, currentmasstextview; button stop; thread updatemass; arraylist<string> indata;  // 2 things when handlemessage method called: // 1) takes recent data read in , calculates current mass it, updates //    current mass text view reflect // 2) takes newly calculated mass , sees if status should change, depending on how //    mass there is. writes value serial port (back arduino) //    depending on status. updates status text view reflect handler updatemasshandler = new handler(){     public void handlemessage(message msg){         // mass calculation         try{currentmassval = calculatemass(integer.parseint(indata.get(indata.size()-1)));} catch (exception e){} // try-catch in case data isn't int         indata.clear();         currentmasstextview.settext(string.format(getresources().getstring(r.string.current_mass_string), currentmassval));          // status check new mass         if (currentmassval >= maxload)             status = true;         else if (currentmassval <= minload)             status = false;         statustextview.settext(string.format(getresources().getstring(r.string.pump_status), getstatus()));          // writing arduino         if (serialport != null) {             if (status)                 serialport.write("1".getbytes());             else                 serialport.write("0".getbytes());         }     } };  // serial port variables: public final string action_usb_permission = "com.example.jake.usb_permission"; usbmanager usbmanager; usbdevice device; usbserialdevice serialport; usbdeviceconnection connection;  usbserialinterface.usbreadcallback mcallback = new usbserialinterface.usbreadcallback() { //defining callback triggers whenever data read.     @override     public void onreceiveddata(byte[] arg0) {         string data;         try {             data = new string(arg0, "utf-8");             indata.add(data);         } catch (unsupportedencodingexception e) {}     } }; private final broadcastreceiver broadcastreceiver = new broadcastreceiver() { //broadcast receiver automatically start , stop serial connection.     @override     public void onreceive(context context, intent intent) {         if (intent.getaction().equals(action_usb_permission)) {             boolean granted = intent.getextras().getboolean(usbmanager.extra_permission_granted);             if (granted) {                 connection = usbmanager.opendevice(device);                 serialport = usbserialdevice.createusbserialdevice(device, connection);                 if (serialport != null) {                     if (serialport.open()) { //set serial connection parameters.                         serialport.setbaudrate(9600);                         serialport.setdatabits(usbserialinterface.data_bits_8);                         serialport.setstopbits(usbserialinterface.stop_bits_1);                         serialport.setparity(usbserialinterface.parity_none);                         serialport.setflowcontrol(usbserialinterface.flow_control_off);                         serialport.read(mcallback);                     } else {                         log.d("serial", "port not open");                     }                 } else {                     log.d("serial", "port null");                 }             } else {                 log.d("serial", "perm not granted");             }         } else if (intent.getaction().equals(usbmanager.action_usb_device_attached)) {             start();         } else if (intent.getaction().equals(usbmanager.action_usb_device_detached)) {             stop();         }     } };  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_pump);     usbmanager = (usbmanager) getsystemservice(usb_service);     intentfilter filter = new intentfilter();     filter.addaction(action_usb_permission);     filter.addaction(usbmanager.action_usb_device_attached);     filter.addaction(usbmanager.action_usb_device_detached);     registerreceiver(broadcastreceiver, filter);      status = false;     statustextview = (textview) findviewbyid(r.id.statustextview);     statustextview.settext(string.format(getresources().getstring(r.string.pump_status), getstatus()));     currentmasstextview = (textview) findviewbyid(r.id.currentmasstextview);     currentmasstextview.settext(r.string.calculating_text);     stop = (button) findviewbyid(r.id.stopbutton);     runtimer = true;     currentmassval = 0;     indata = new arraylist<>();      // thread "calls" handlemessage method in updatemasshandler every 100 milliseconds     updatemass = new thread(new runnable() {         @override         public void run() {             while(runtimer){                 updatemasshandler.sendemptymessage(0);                 try{thread.sleep(100);} catch (interruptedexception e){}             }         }     });      // stackoverflow file reading code     // reading , parsing calibration data     calibrationdata = new file(getfilesdir(), "calibrationdata.txt");      stringbuilder text = new stringbuilder();      // reading in calibration data file (of same name)     try {         bufferedreader br = new bufferedreader(new filereader(calibrationdata));         string line;          while ((line = br.readline()) != null) {             text.append(line);             text.append('\n');         }         br.close();     } catch (ioexception e) {}      // parsing values calibration data     string calibdata = text.tostring();     calibdata = calibdata.substring(3);     mass1 = integer.parseint(calibdata.substring(0, calibdata.indexof('r')));     calibdata = calibdata.substring(calibdata.indexof(':') + 1);     read1 = integer.parseint(calibdata.substring(0, calibdata.indexof('m')));     calibdata = calibdata.substring(calibdata.indexof(':') + 1);     mass2 = integer.parseint(calibdata.substring(0, calibdata.indexof('r')));     calibdata = calibdata.substring(calibdata.indexof(':') + 1);     read2 = integer.parseint(calibdata.substring(0, calibdata.indexof('.')));      slope = ((double) (mass2 - mass1) / (read2 - read1)); // calculating slope of masses , reads allow                                                           // calculation of mass of unknown read      // reading , parsing bag data     bagdata = new file(getfilesdir(), "bagdata.txt");      stringbuilder text2 = new stringbuilder();      // reading in bag data file (of same name)     try {         bufferedreader br = new bufferedreader(new filereader(bagdata));         string line;          while ((line = br.readline()) != null) {             text2.append(line);             text2.append('\n');         }         br.close();     } catch (ioexception e) {}      // parsing values frm bag data     string bagdata = text2.tostring();     bagdata = bagdata.substring(1);     emptymassnum = integer.parseint(bagdata.substring(0, bagdata.indexof('m')));     bagdata = bagdata.substring(bagdata.indexof('x') + 1);     maxload = float.parsefloat(bagdata.substring(0, bagdata.indexof('m')));     bagdata = bagdata.substring(bagdata.indexof('n') + 1);     minload = float.parsefloat(bagdata.substring(0, bagdata.indexof(';')));      emptymass = calculatemass(emptymassnum); // emptymassnum values read in arduino                                              // converts mass      updatemass.start();     start(); }  // method: calculatemass // description: calculates mass of object on transducer based off of value read //              in , data gotten calibration // input: int readval - value read in // output: double - calculated mass public double calculatemass(int readval){     return (slope * (readval-read1)) + mass1; }  // method: getstatus // description: returns string representation of status public string getstatus(){     if(status)         return "running";     else         return "stopped"; }  // method: stop // description: stops when stop button pressed public void stop(view view){     status = false;     runtimer = false;     stop();     stop.settext(r.string.button_stopped); }  // serial port methods: public void start() {     hashmap<string, usbdevice> usbdevices = usbmanager.getdevicelist();     if (!usbdevices.isempty()) {         boolean keep = true;         (map.entry<string, usbdevice> entry : usbdevices.entryset()) {             device = entry.getvalue();             int devicevid = device.getvendorid();             if (devicevid == 10755 || devicevid == 9025)//arduino vendor id             {                 pendingintent pi = pendingintent.getbroadcast(this, 0, new intent(action_usb_permission), 0);                 usbmanager.requestpermission(device, pi);                 keep = false;             } else {                 connection = null;                 device = null;             }              if (!keep)                 break;         }     } }  public void stop() {     if(serialport!=null)         serialport.close(); } } 

for reason, onreceiveddata method in mcallback variable not seem called in second activity (the 1 not working). i'm pretty sure problem, i'm not sure why being called in 1 activity , not in same code. if method not called, can't access data coming in, problem.

also, here's manifest:

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.stylosa.hangingtransducer">  <uses-feature android:name="android.hardware.usb.host" />  <uses-permission android:name="android.permission.write_external_storage" />  <application     android:allowbackup="true"     android:icon="@mipmap/ic_launcher"     android:label="@string/app_name"     android:roundicon="@mipmap/ic_launcher_round"     android:supportsrtl="true"     android:theme="@style/apptheme">     <activity android:name=".mainactivity">         <intent-filter>             <action android:name="android.intent.action.main" />              <category android:name="android.intent.category.launcher" />         </intent-filter>         <intent-filter>             <action android:name="android.hardware.usb.action.usb_device_attached" />         </intent-filter>         <intent-filter>             <action android:name="android.hardware.usb.action.usb_device_detached" />         </intent-filter>     </activity>     <activity         android:name=".calibrateactivity">         <intent-filter>             <action android:name="android.hardware.usb.action.usb_device_attached" />         </intent-filter>         <intent-filter>             <action android:name="android.hardware.usb.action.usb_device_detached" />         </intent-filter>     </activity>     <activity         android:name=".inputactivity"         android:parentactivityname=".mainactivity">         <intent-filter>             <action android:name="android.hardware.usb.action.usb_device_attached" />         </intent-filter>         <intent-filter>             <action android:name="android.hardware.usb.action.usb_device_detached" />         </intent-filter>     </activity>     <activity         android:name=".enterdataactivity">         <intent-filter>             <action android:name="android.hardware.usb.action.usb_device_attached" />         </intent-filter>         <intent-filter>             <action android:name="android.hardware.usb.action.usb_device_detached" />         </intent-filter>     </activity>     <activity         android:name=".pumpactivity">         <intent-filter>             <action android:name="android.hardware.usb.action.usb_device_attached" />         </intent-filter>         <intent-filter>             <action android:name="android.hardware.usb.action.usb_device_detached" />         </intent-filter>     </activity> </application> 

any , appreciated!