Checking Connection to Server in Android Studio

Question

Just as the title suggest, I have a problem with checking android connection to the server.

I have a project that I left for some month, back then the code that I used to check the server's connection was the answer from this question, but now when I opened this project again and try to run it, I can't seem to be able to reach the server.

This is my code to check the server's connection :

public static boolean isServerConnected() {
    try {
        URL myUrl = new URL(URL_CONNECTION);
        URLConnection connection = myUrl.openConnection();
        connection.setConnectTimeout(10000);
        connection.connect();
        return true;
    } catch (Exception e) {
        e.printStackTrace();
        return false;
    }
}

And this is where I call it (in a login button) :

btnLogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            if (Servers.isServerConnected()) {
                username = edtUser.getText().toString();
                password = edtPass.getText().toString();
                login();
            } else {
                Toast.makeText(getApplicationContext(), "Server is not connected", Toast.LENGTH_SHORT).show();
            }
        }
    });

This is the exception that I got :

D/NetworkSecurityConfig: No Network Security Config specified, using platform default
W/System.err: android.os.NetworkOnMainThreadException
    at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1303)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:333)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:196)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:178)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:356)
    at java.net.Socket.connect(Socket.java:586)
    at com.android.okhttp.internal.Platform.connectSocket(Platform.java:113)
    at com.android.okhttp.Connection.connectSocket(Connection.java:196)
    at com.android.okhttp.Connection.connect(Connection.java:172)
    at com.android.okhttp.Connection.connectAndSetOwner(Connection.java:367)
    at com.android.okhttp.OkHttpClient$1.connectAndSetOwner(OkHttpClient.java:130)
    at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:329)
    at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:246)
    at 
com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:457)
    at 
com.android.okhttp.internal.huc.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:126)
    at com.itats.huwenakapp.koneksi.Servers.isServerConnected(Servers.java:38)
    at com.itats.huwenakapp.Login$1.onClick(Login.java:74)
    at android.view.View.performClick(View.java:5610)
    at 
com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1119)
    at android.view.View$PerformClick.run(View.java:22265)
W/System.err:     at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6077)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)

Answer 1

As stated in the exception log you are getting android.os.NetworkOnMainThreadException this occurs when you are performing a network call on Main Thread / UI Thread of android. To resolve this issue you have to perform the call on a background thread. This could include using a AsyncTask (depricated) or Coroutines (only for Kotlin) or RxJava or any other threading way to run the the call on background thread.

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