unable tou understand exceptions while creating a simple client socket

Question

I am trying to create a simple client socket in android studio but I am unable to do and unable to understand exceptions. My app crashes whenever i try to create connection. There is a only button on my app named 'Button'

public class MainActivity extends AppCompatActivity {

Socket s;
Button con;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    con = (Button)findViewById(R.id.button);
}
public void connect(View view)
{
    try {


        s = new Socket("192.168.12.178", 22222);

        if (s.isConnected())
        {
            Toast.makeText(getApplicationContext(), "Socket is Connected", Toast.LENGTH_SHORT).show();
        }
    } catch (IOException e) {
        e.printStackTrace();
    }

}
}

--------- beginning of crash

06-06 23:11:49.143 22703-22703/com.example.test1 E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.test1, PID: 22703
    java.lang.IllegalStateException: Could not execute method for android:onClick
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:390)
        at android.view.View.performClick(View.java:5198)
        at android.view.View$PerformClick.run(View.java:21147)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:148)
        at android.app.ActivityThread.main(ActivityThread.java:5417)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385)
        at android.view.View.performClick(View.java:5198) 
        at android.view.View$PerformClick.run(View.java:21147) 
        at android.os.Handler.handleCallback(Handler.java:739) 
        at android.os.Handler.dispatchMessage(Handler.java:95) 
        at android.os.Looper.loop(Looper.java:148) 
        at android.app.ActivityThread.main(ActivityThread.java:5417) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
     Caused by: android.os.NetworkOnMainThreadException
        at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1273)
        at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:110)
        at libcore.io.IoBridge.connectErrno(IoBridge.java:137)
        at libcore.io.IoBridge.connect(IoBridge.java:122)
        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:183)
        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:163)
        at java.net.Socket.startupSocket(Socket.java:592)
        at java.net.Socket.tryAllAddresses(Socket.java:128)
        at java.net.Socket.<init>(Socket.java:178)
        at java.net.Socket.<init>(Socket.java:150)
        at com.example.test1.MainActivity.connect(MainActivity.java:29)
        at java.lang.reflect.Method.invoke(Native Method) 
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385) 
        at android.view.View.performClick(View.java:5198) 
        at android.view.View$PerformClick.run(View.java:21147) 
        at android.os.Handler.handleCallback(Handler.java:739) 
        at android.os.Handler.dispatchMessage(Handler.java:95) 
        at android.os.Looper.loop(Looper.java:148) 
        at android.app.ActivityThread.main(ActivityThread.java:5417) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

score 0 · Answer 1 · answered Jun 07 '19 at 18:35

0

The exception is: Caused by: android.os.NetworkOnMainThreadException If you try to do an network operation on MainThread this exception will raise. You must do it on a Background thread, you can see how here: https://developer.android.com/reference/android/os/AsyncTask

answered Jun 07 '19 at 18:35

Shermano

1,100
8
31

how can i handle events for multiple buttons of main thread in 'doInBackground' of AsyncTask ? – Bilal Hassan Jun 12 '19 at 20:08
check this one: https://stackoverflow.com/questions/9671546/asynctask-android-example , I hope the correct answer of this post can help you – Shermano Jun 12 '19 at 20:37

score 0 · Answer 2 · answered Jun 07 '19 at 18:36

0

I'm pretty sure your main issue is: "Caused by: android.os.NetworkOnMainThreadException" which is thrown at MainActivity.java line 29 and it's being thrown because you're making a network request on the main UI thread which you can't do because it would hang up the UI thread. Try using an AsyncTask.

answered Jun 07 '19 at 18:36

LinuxMasterRace

107
6

how can i handle events for multiple buttons of main thread in 'doInBackground' of AsyncTask ? – Bilal Hassan Jun 12 '19 at 20:08

unable tou understand exceptions while creating a simple client socket

2 Answers2