When you try to connect with web server you got the following exception:

java.net.SocketException: socket failed: EACCES (Permission denied)
        at java.net.Socket.createImpl(Socket.java:492)
        at java.net.Socket.getImpl(Socket.java:552)
        at java.net.Socket.setSoTimeout(Socket.java:1180)
        at okhttp3.internal.connection.RealConnection.connectSocket(RealConnection.java:244)
        at ...
okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:254)
        at okhttp3.RealCall$AsyncCall.execute(RealCall.java:200)
        at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at java.lang.Thread.run(Thread.java:914)

Solution: Add security permission

The cause of the exception is that the application has no permission to connect to the Internet. To add missing permissions just open AndsroidManifest.xml file and ass the following lines:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example">
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>