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I’m doing academic work where I’m developing an Android app that controls a robot simulation done in Python. I’m trying to communicate through a socket where pressing a key in the app sends the command of a certain letter so that the robot moves. I used as a basis some examples found here, but I believe I have not applied them correctly since the app (client) is not connecting with the application in python (server), I would like to know what I am doing wrong.
Edit: Updating the code with what was suggested in the comment, now by pressing a button with the event, the app crasha. The code of the Commsocket class and the Python application are up to date. I also added a log excerpt I collected from the phone at the time the application crashes. Improving the understanding of the situation, the test is done on a mobile phone and the application in python runs on a computer, both connected on the same network.
Python application code:
import socket
import rospy
from geometry_msgs.msg import Twist
import sys, select, os
if os.name == 'nt':
import msvcrt
else:
import tty, termios
if __name__=="__main__":
HOST = '198.162.0.10' # Endereco IP do Servidor
PORT = 6789 # Porta que o Servidor esta
queue = 5
bufferSize = 256
tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
orig = (HOST, PORT)
tcp.bind(orig)
tcp.listen(queue)
try:
print(msg)
while(1):
# key = getKey()
con, cliente = tcp.accept()
print ('Concetado por', cliente)
key = con.recv(bufferSize)
if key == 'w' :
target_linear_vel = checkLinearLimitVelocity(target_linear_vel + LIN_VEL_STEP_SIZE)
status = status + 1
print(vels(target_linear_vel,target_angular_vel))
elif key == 'x' :
target_linear_vel = checkLinearLimitVelocity(target_linear_vel - LIN_VEL_STEP_SIZE)
status = status + 1
print(vels(target_linear_vel,target_angular_vel))
elif key == 'a' :
target_angular_vel = checkAngularLimitVelocity(target_angular_vel + ANG_VEL_STEP_SIZE)
status = status + 1
print(vels(target_linear_vel,target_angular_vel))
elif key == 'd' :
target_angular_vel = checkAngularLimitVelocity(target_angular_vel - ANG_VEL_STEP_SIZE)
status = status + 1
print(vels(target_linear_vel,target_angular_vel))
elif key == ' ' or key == 's' :
target_linear_vel = 0.0
control_linear_vel = 0.0
target_angular_vel = 0.0
control_angular_vel = 0.0
print(vels(target_linear_vel, target_angular_vel))
else:
if (key == '\x03'):
break
con.close()
Commsocket.java
import android.os.AsyncTask;
import android.os.Handler;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.SocketAddress;
import java.util.Arrays;
public class CommSocket extends AsyncTask<String, Integer, String>{
private static final String hostname = "localhost";
private static final String addr = "198.162.0.10";
private static final int portaServidor = 6789;
private IAsyncHandler mHandler;
public CommSocket(IAsyncHandler mHandler) {
this.mHandler = mHandler;
}
@Override
protected String doInBackground(String... params) {
try {
Socket socket = new Socket(addr, portaServidor);
//SocketAddress socket = new InetSocketAddress(addr, portaServidor);
//dados enviados para o servidor
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
//Estou usando Arrays.toString(), somente para ele pegar todas as strings que passar no
//método.
bw.write(Arrays.toString(params));
bw.newLine();
bw.flush();
//dados recebidos pelo servidor
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String retorno = "Dados cadastrados " + br.readLine(); //retornar ok
socket.close();
return retorno;
}
catch(IOException e) {
return e.getMessage();
}
}
@Override
protected void onPostExecute(String result) {
mHandler.postResult(result);
}
}
Mainactivity.java
import android.os.Bundle;
import android.view.View;
import android.view.Menu;
import android.widget.TextView;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;
import com.google.android.material.navigation.NavigationView;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
import com.example.tcc_wheelchair.CommSocket;
public class MainActivity extends AppCompatActivity implements IAsyncHandler{
private AppBarConfiguration mAppBarConfiguration;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//CommSocket task = new CommSocket(MainActivity.this);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
DrawerLayout drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
mAppBarConfiguration = new AppBarConfiguration.Builder(
R.id.nav_home, R.id.nav_gallery)
.setDrawerLayout(drawer)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
}
public void eventClickStop (View view)
{
TextView texto = findViewById(R.id.textViewteste);
texto.setText("STOP");
CommSocket task = new CommSocket(MainActivity.this);
task.doInBackground("s");
}
public void eventClickUp (View view)
{
TextView texto = findViewById(R.id.textViewteste);
texto.setText("UP ARROW");
CommSocket task = new CommSocket(MainActivity.this);
task.doInBackground("w");
}
public void eventClickDown (View view)
{
TextView texto = findViewById(R.id.textViewteste);
texto.setText("DOWN ARROW");
CommSocket task = new CommSocket(MainActivity.this);
task.doInBackground("x");
}
public void eventClickRight (View view)
{
TextView texto = findViewById(R.id.textViewteste);
texto.setText("RIGHT ARROW");
CommSocket task = new CommSocket(MainActivity.this);
task.doInBackground("d");
}
public void eventClickLeft (View view)
{
TextView texto = findViewById(R.id.textViewteste);
texto.setText("LEFT ARROW");
CommSocket task = new CommSocket(MainActivity.this);
task.doInBackground("a");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onSupportNavigateUp() {
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
return NavigationUI.navigateUp(navController, mAppBarConfiguration)
|| super.onSupportNavigateUp();
}
@Override
public void postResult(String result) {
//Neste método você pega o resultado da asynctask e aproveita de alguma forma
}
}
interface IAsyncHandler {
void postResult(String result);
}
Cell phone log:
--------- beginning of crash
06-03 23:07:52.266 9374 9374 E AndroidRuntime: FATAL EXCEPTION: main
06-03 23:07:52.266 9374 9374 E AndroidRuntime: Process: com.example.tcc_wheelchair, PID: 9374
06-03 23:07:52.266 9374 9374 E AndroidRuntime: java.lang.IllegalStateException: Could not execute method for android:onClick
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:414)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at android.view.View.performClick(View.java:6608)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at android.view.View.performClickInternal(View.java:6585)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at android.view.View.access$3100(View.java:785)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at android.view.View$PerformClick.run(View.java:25921)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at android.os.Handler.handleCallback(Handler.java:873)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:99)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at android.os.Looper.loop(Looper.java:201)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:6864)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: Caused by: java.lang.reflect.InvocationTargetException
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: ... 11 more
06-03 23:07:52.266 9374 9374 E AndroidRuntime: Caused by: android.os.NetworkOnMainThreadException
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1513)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:389)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:230)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:212)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:436)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at java.net.Socket.connect(Socket.java:621)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at java.net.Socket.connect(Socket.java:570)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at java.net.Socket.<init>(Socket.java:450)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at java.net.Socket.<init>(Socket.java:218)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at com.example.tcc_wheelchair.CommSocket.doInBackground(CommSocket.java:31)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: at com.example.tcc_wheelchair.MainActivity.eventClickUp(MainActivity.java:112)
06-03 23:07:52.266 9374 9374 E AndroidRuntime: ... 13 more
06-03 23:07:52.357 1682 2970 W ActivityManager: Force finishing activity com.example.tcc_wheelchair/.MainActivity
06-03 23:07:52.378 1682 1849 W BroadcastQueue: Background execution not allowed: receiving Intent { act=android.intent.action.DROPBOX_ENTRY_ADDED flg=0x10 (has extras) } to com.google.android.gms/.stats.service.DropBoxEntryAddedReceiver
06-03 23:07:52.378 1682 1849 W BroadcastQueue: Background execution not allowed: receiving Intent { act=android.intent.action.DROPBOX_ENTRY_ADDED flg=0x10 (has extras) } to com.google.android.gms/.chimera.GmsIntentOperationService$PersistentTrustedReceiver
06-03 23:07:52.382 1682 3467 D ActivityManager: report kill process: killerPid is:9374, killedPid is:9374
06-03 23:07:52.473 1682 2317 I WindowManager: WIN DEATH: Window{9e15302 u0 com.example.tcc_wheelchair/com.example.tcc_wheelchair.MainActivity}
06-03 23:07:52.474 1682 1776 I ActivityManager: Process com.example.tcc_wheelchair (pid 9374) has died: vis TOP
06-03 23:07:52.475 1682 1776 D ProcessManager: skip restart com.example.tcc_wheelchair because of low mem!
06-03 23:07:52.514 1682 1776 I Timeline: Timeline: App_transition_ready time:22000511
06-03 23:07:52.515 1682 1857 W ActivityManager: setHasOverlayUi called on unknown pid: 9374
06-03 23:07:52.522 1682 2448 I Timeline: Timeline: App_transition_ready time:22000519
06-03 23:07:52.537 1682 1929 V UiModeManager: switch night mode to 2
06-03 23:07:52.561 1682 1968 D ActivityManagerServiceInjector: Begin to report package foreground events...
06-03 23:07:52.564 1682 3467 I Timeline: Timeline: App_transition_ready time:22000560
06-03 23:07:52.576 1682 3467 I Timeline: Timeline: App_transition_ready time:22000572
06-03 23:07:52.621 1682 1929 V UiModeManager: switch night mode to 2
06-03 23:07:52.626 1682 3467 I Timeline: Timeline: App_transition_ready time:22000622
06-03 23:07:52.661 1682 1906 I Timeline: Timeline: App_transition_ready time:22000657
06-03 23:07:52.661 1682 1906 I Timeline: Timeline: App_transition_stopped time:22000657
06-03 23:07:52.668 1682 1857 I Timeline: Timeline: Activity_windows_visible id: ActivityRecord{c776715 u0 com.mi.android.globalFileexplorer/com.android.fileexplorer.activity.FileCategoryActivity t23447} time:22000665
06-03 23:07:52.713 1682 2969 I ActivityManager: Killing 7563:com.android.vending:download_service/u0a42 (adj 906): empty #17
06-03 23:07:52.740 1682 2436 D ConnectivityService: ConnectivityService NetworkRequestInfo binderDied(NetworkRequest [ TRACK_DEFAULT id=569, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED Unwanted: Uid: 10042] ], android.os.BinderProxy@9406917)
06-03 23:07:52.741 1682 1946 D ConnectivityService: releasing NetworkRequest [ TRACK_DEFAULT id=569, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED Unwanted: Uid: 10042] ] (release request)
06-03 23:07:52.741 1682 2970 D ProcessManager: skip restart com.android.vending:download_service because of low mem!
06-03 23:07:53.080 1682 2970 I ActivityManager: Killing 7770:com.google.android.gms.unstable/u0a30 (adj 906): empty #17
06-03 23:07:53.153 1682 2448 D ProcessManager: skip restart com.google.android.gms.unstable because of low mem!
06-03 23:07:55.004 1682 2448 W BaseMiuiPhoneWindowManager: keyCode:3 down:true eventTime:22002999 downTime:22002999 policyFlags:2b000002 flags:48 deviceId:-1 isScreenOn:true keyguardActive:false repeatCount:0
06-03 23:07:55.167 1682 2448 W BaseMiuiPhoneWindowManager: keyCode:3 down:false eventTime:22003163 downTime:22002999 policyFlags:2b000002 flags:48 deviceId:-1 isScreenOn:true keyguardActive:false repeatCount:0
06-03 23:07:55.253 1682 1921 I ActivityManager: START u0 {act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10200000 cmp=com.miui.home/.launcher.Launcher (has extras)} from uid 1000
Thanks for the reply, with these modifications when clicking on a button corresponding to the actions, the app crasha. The test is being done on a mobile device and the script running on the PC, both connected on the same network. Have any idea what it might be?
– DLourenco
Update the question with the new code and with any error message you have access to to help better.
– Emerson Pardo
Hello Emerson, I edited the question and added a log. Thank you.
– DLourenco
I never programmed for android but the Asynctask documentation ( https://developer.android.com/reference/android/os/AsyncTask ) says that you should not call doInBackground directly, so that the execution actually happens asynchronously, you should call the API execute method by passing the parameters. In your code it would be, for example, like this
task.execute("w")instead oftask.doInBackground("w"). Also note that this class is obsolete (@Deprecated) and that in future versions your code may stop working.– Emerson Pardo
In this reply there is a brief explanation of why your code has failed: https://stackoverflow.com/a/22395546/4712790
– Emerson Pardo