CODEWITHSUNDEEP
android
dragullar
dragullar

Reputation: 355

How to solve socket instantiate error ?

I try to connect android to printer via wifi, I got error NetworkOnMainThreadException.

Here is my code :

public void OnClickPrint(View paramView) {  
    File file = new File(DB_PATH);
    try {
    Socket  client = new Socket("172.230.1.16", 9100);

        byte[] mybytearray = new byte[(int) file.length()]; 

        fileInputStream = new FileInputStream(file);
        bufferedInputStream = new BufferedInputStream(fileInputStream);

        bufferedInputStream.read(mybytearray, 0, mybytearray.length);                                                                   
        outputStream = client.getOutputStream();

        outputStream.write(mybytearray, 0, mybytearray.length); //
        outputStream.flush();
        bufferedInputStream.close();
        outputStream.close();
        client.close();

    } catch (UnknownHostException e) {
        Log.v("a", e.getMessage());
        e.printStackTrace();
    } catch (IOException e) {
        Log.v("a", e.getMessage());
        e.printStackTrace();
    }
}

When I trace code by F6 , I got errors socket instantiate at Socket client = new Socket("172.230.1.16", 9100); 172.230.1.16 is my printer ip.

Error logcat:

    02-28 09:44:40.572: E/AndroidRuntime(1426): FATAL EXCEPTION: main
    02-28 09:44:40.572: E/AndroidRuntime(1426): java.lang.IllegalStateException: Could not execute method of the activity
    02-28 09:44:40.572: E/AndroidRuntime(1426): at android.view.View$1.onClick(View.java:3044)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at android.view.View.performClick(View.java:3511)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at android.view.View$PerformClick.run(View.java:14105)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at android.os.Handler.handleCallback(Handler.java:605)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at android.os.Handler.dispatchMessage(Handler.java:92)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at android.os.Looper.loop(Looper.java:137)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at android.app.ActivityThread.main(ActivityThread.java:4424)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at java.lang.reflect.Method.invokeNative(Native Method)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at java.lang.reflect.Method.invoke(Method.java:511)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at dalvik.system.NativeStart.main(Native Method)
    02-28 09:44:40.572: E/AndroidRuntime(1426): Caused by: java.lang.reflect.InvocationTargetException
    02-28 09:44:40.572: E/AndroidRuntime(1426): at  java.lang.reflect.Method.invokeNative(Native Method)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at java.lang.reflect.Method.invoke(Method.java:511)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at android.view.View$1.onClick(View.java:3039)
    02-28 09:44:40.572: E/AndroidRuntime(1426):     ... 11 more
    02-28 09:44:40.572: E/AndroidRuntime(1426): Caused by: android.os.NetworkOnMainThreadException
    02-28 09:44:40.572: E/AndroidRuntime(1426): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at libcore.io.IoBridge.connect(IoBridge.java:112)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at java.net.Socket.startupSocket(Socket.java:566)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at java.net.Socket.tryAllAddresses(Socket.java:127)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at java.net.Socket.<init>(Socket.java:177)
    02-28 09:44:40.572: E/AndroidRuntime(1426): at java.net.Socket.<init>(Socket.java:149)
    02-28 09:44:40.572: E/AndroidRuntime(1426):     at com.example.printertest.MainActivity.OnClickPrint(MainActivity.java:56)

How to solve it ?

Upvotes: 1

Views: 143

Answers (1)

Lucifer
Lucifer

Reputation: 29632

Caused by: android.os.NetworkOnMainThreadException

You are performing Network operations on Main Thread of Android OS. I suggest you to use AsyncTask. You should perform a long running Network Operations in AsyncTask. AsyncTask enables proper and easy use of the UI thread. This class allows to perform background operations and publish results on the UI thread without having to manipulate threads and/or handlers.

public void OnClickPrint(View paramView) 
{ 
    new PrintFile().execute();
}

private class PrintFile extends AsyncTask<Void, Void, Void>
{
    @Override
    protected Void doInBackground(Void... result) 
    {
        File file = new File(DB_PATH);
        try {
        Socket  client = new Socket("172.230.1.16", 9100);

            byte[] mybytearray = new byte[(int) file.length()]; 

            fileInputStream = new FileInputStream(file);
            bufferedInputStream = new BufferedInputStream(fileInputStream);

            bufferedInputStream.read(mybytearray, 0, mybytearray.length);                                                                   
            outputStream = client.getOutputStream();

            outputStream.write(mybytearray, 0, mybytearray.length); //
            outputStream.flush();
            bufferedInputStream.close();
            outputStream.close();
            client.close();

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

Upvotes: 2

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