Why does the following lines of code throw an IllegalStateException?

Question

I want to connect an android app to a server with java's ServerSocket and Socket classes. I am using the following line at the client to connect to the server:

var socket = new Socket(InetAddress.getByName("192.168.1.21"), 59090);

("192.168.1.21" is my computer's ip) Now, when I'm opening a simple java project file it is working, but when I'm trying this line in an android project and I run it through a simulator it throws the said exception and crashes. Does anybody know why?

Please edit your question and post the complete stack trace associated with the crash. — CommonsWare, Dec 01 '19 at 20:41
Please don't post screenshots of code, XML, or logcat output. Please post all text as text. — Mike M., Dec 01 '19 at 20:54

score 1 · Answer 1 · 2019-12-01T21:02:26.600

1

The stack trace shows the problem is that a NetworkOnMainThreadException was thrown.

The documentation for that exception says you can't do network operations on your main thread.

As for how I knew where to look: the stack trace says that the IllegalStateException was caused by an InvocationTargetException which was caused by a NetworkOnMainThreadException.

edited Dec 01 '19 at 21:02

answered Dec 01 '19 at 20:56

score 1 · Answer 2 · answered Dec 01 '19 at 21:02

1

you need to create AsyncTask and create new Socket within AsyncTask. You can't make a network call inside UI main thread.

answered Dec 01 '19 at 21:02

Don Ha

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Why does the following lines of code throw an IllegalStateException?

2 Answers2