How to use async task results in if statement

Question

I want to check the internet connection with a particular website before starting a method in my onClick. After doing some research I found this link who's accepted answer showed me how to do that Android Internet connectivity check better method the problem is though the method produces error android os networkonmainthreadexception, I did more research and found out that such an operation was required to be run in async task. How can I do this and still use the result in my button onClick method.

This is my current code in onCreate.

  @Override
  public void onClick(View view) {
      if (isInternetAvailable("18.184.67.80", 443, 1000)) {
          Method() ;
      } else {
          Toast.makeText(getApplicationContext)) , "Internet not available" ).show;
      }
  }

Below is the code for checking internet connection with site

   public boolean isInternetAvailable(String address, int port, int timeoutMs) {
       try {
            Socket sock = new Socket();
            SocketAddress sockaddr = new InetSocketAddress(address, port);

            sock.connect(sockaddr, timeoutMs); // This will block no more than timeoutMs
            sock.close();

            return true;

       } catch (IOException e) { 
            return false; 
       }
   }

How would I use the above code in an async task and use results as to whether there is no internet connection or not in the if statement in the oncreate method?

Earlier on I also found this How to check internet access on Android? InetAddress never times out but I don't understand what code I would use to derive the results from the async task and use them in the oncreate under onClick.

The general solution is to make a `Future` of some sort (through an `ExecutorService`/`ThreadPool`), and then after it completes, execute on the results. The point here is to not block the main thread (e.g. waiting on I/O), so `CompletableFuture` here is handy as you can use `#whenComplete` etc to execute a task after the completion with use of lambdas / the function api — Rogue, Oct 19 '19 at 18:46

score 0 · Accepted Answer · answered Oct 19 '19 at 19:09

You can start an AsyncTask to check for internet availability in onClick() and in the AsyncTasks's onPostExecute() you can update the UI based on the result.

Since AsyncTask.execute() takes only one parameter, you can use a wrapper class to pass in address, port and timeOutMs:

class InetAddress{
    public InetAddress(String address, int port, int timeoutMs){
        this.address = address;
        this.port = port;
        this.timeOutAfterMs = timeoutMs;
    }

    String address;
    int port;
    int timeOutAfterMs;
}

AsyncTask code:

class InternetCheckTask extends AsyncTask<InetAddress, Void, Boolean> {

    @Override
    protected Boolean doInBackground(InetAddress... inetAddresses) {
        try {
            InetAddress inetAddress = inetAddresses[0];
            Socket sock = new Socket();
            SocketAddress sockaddr = new InetSocketAddress(inetAddress.address, inetAddress.port);

            sock.connect(sockaddr, inetAddress.timeOutAfterMs); // This will block no more than timeoutMs
            sock.close();

            return true;

        } catch (IOException e) { return false; }
    }

    @Override
    protected void onPostExecute(Boolean isInternetAvailable) {
        // Note: this will be executed on the main thread
        if(isInternetAvailable){
            doSomething();
        }
        else{
            Toast.makeText(MainActivity.this , "Internet not available", Toast.LENGTH_SHORT ).show();
        }
    }
}

Start it in onClick() like this:

@Override
public void onClick(View view) {
    InetAddress inetAddress = new InetAddress("18.184.67.80", 443, 1000);
    new InternetCheckTask().execute(inetAddress);
}

How to use async task results in if statement

1 Answers1