New debug preference: show connection errors pop-ups (disabled by default).

app/src/main/java/com/xabber/android/data/SettingsManager.java

@@ -450,6 +450,10 @@ public class SettingsManager implements OnInitializedListener,
         return getBoolean(R.string.debug_log_key, R.bool.debug_log_default);
     }
 
+    public static boolean showConnectionErrors() {
+        return getBoolean(R.string.debug_connection_errors_key, R.bool.debug_connection_errors_default);
+    }
+
     public static InterfaceTheme interfaceTheme() {
         String value = getString(R.string.interface_theme_key,
                 R.string.interface_theme_default);

app/src/main/java/com/xabber/android/data/connection/ConnectionThread.java

@@ -20,6 +20,7 @@ import com.xabber.android.R;
 import com.xabber.android.data.Application;
 import com.xabber.android.data.LogManager;
 import com.xabber.android.data.NetworkException;
+import com.xabber.android.data.SettingsManager;
 import com.xabber.android.data.account.AccountItem;
 import com.xabber.android.data.account.AccountProtocol;
 import com.xabber.android.data.account.OAuthManager;
@@ -533,15 +534,17 @@ public class ConnectionThread implements
         if (checkForSeeOtherHost(e))
             return;
 
+        if (SettingsManager.showConnectionErrors()) {
             runOnUiThread(new Runnable() {
                 @Override
                 public void run() {
                     Toast.makeText(Application.getInstance(),
                             Application.getInstance().getString(R.string.CONNECTION_FAILED) + ": " + e.getMessage(),
-                        Toast.LENGTH_LONG
+                            Toast.LENGTH_SHORT
                     ).show();
                 }
             });
+        }
 
         connectionClosed();
     }

app/src/main/res/values/preference_editor.xml

@@ -78,4 +78,5 @@
     <string name="connection_use_carbons">Carbon-copied mode\nMay be unstable! Will share sessions for the same account on this client. Disable to reduce traffic usage.</string>
     <string name="events_phrases">Key phrases\nCreate custom notifications for received messages that contain specific phrases</string>
     <string name="security_clear_certificate_warning">Do you really want to remove all ignored certificates?</string>
+    <string name="debug_connection_errors_title">Show connection errors\nDisplay connection exceptions pop-ups</string>
 </resources>

app/src/main/res/values/preferences.xml

@@ -353,13 +353,15 @@
     <string name="connection_use_carbons_key">connection_use_carbons</string>
     <bool name="connection_use_carbons_default">false</bool>
 
-<!-- preference_cache -->
+<!-- preference_debug -->
     <string name="cache_clear_key">cache_clear</string>
 
-<!-- preference_debug -->
     <string name="debug_log_key">debug_log</string>
     <bool name="debug_log_default">true</bool>
 
+    <string name="debug_connection_errors_key">connection_errors</string>
+    <bool name="debug_connection_errors_default">false</bool>
+
 <!-- preference_about -->
     <string name="preference_about">@string/about_viewer</string>
     <string name="preference_about_key">preference_about</string>

app/src/main/res/xml/preference_debug.xml

@@ -9,4 +9,11 @@
         android:title="@string/cache_clear"
         android:key="@string/cache_clear_key"
         android:dialogMessage="@string/cache_clear_warning"/>
+
+    <CheckBoxPreference
+        android:title="@string/debug_connection_errors_title"
+        android:key="@string/debug_connection_errors_key"
+        android:defaultValue="@bool/debug_connection_errors_default"
+        />
+
 </PreferenceScreen>
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