simplify URL validation

app/src/main/java/org/traccar/client/MainActivity.java

@@ -290,26 +290,19 @@ public class MainActivity extends PreferenceActivity implements OnSharedPreferen
     }
 
     private boolean validateServerURL(String userUrl) {
-        EditTextPreference preference = (EditTextPreference) findPreference(KEY_URL);
-
         if (userUrl == null || userUrl.trim().length() == 0) {
+            EditTextPreference preference = (EditTextPreference) findPreference(KEY_URL);
             preference.setText(getString(R.string.settings_url_default_value));
-            preference.setSummary(R.string.settings_url_summary);
-            findPreference(KEY_STATUS).setEnabled(true);
             return false;
         }
         int port = Uri.parse(userUrl).getPort();
         if (URLUtil.isValidUrl(userUrl) && (port >= -1 && port <= 65535)
                 && (URLUtil.isHttpUrl(userUrl) || URLUtil.isHttpsUrl(userUrl))) {
-            preference.setSummary(R.string.settings_url_summary);
-            findPreference(KEY_STATUS).setEnabled(true);
-        } else {
-            preference.setSummary(R.string.error_invalid_url_summary);
-            findPreference(KEY_STATUS).setEnabled(false);
-            Toast.makeText(MainActivity.this, R.string.error_msg_invalid_url, Toast.LENGTH_LONG).show();
-        }
             return true;
         }
+        Toast.makeText(MainActivity.this, R.string.error_msg_invalid_url, Toast.LENGTH_LONG).show();
+        return false;
+    }
 
     private void migrateLegacyPreferences(SharedPreferences preferences) {
         String port = preferences.getString("port", null);

app/src/main/java/org/traccar/client/ProtocolFormatter.java

@@ -38,7 +38,6 @@ public class ProtocolFormatter {
         if (alarm != null) {
             builder.appendQueryParameter("alarm", alarm);
         }
-
         int port = serverUrl.getPort();
         if (port == -1) {
             builder.encodedAuthority(serverUrl.getHost() + ":" + 5055);

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

@@ -43,5 +43,4 @@
   <string name="hidden_app_name">Device Settings</string>
   <string name="hidden_alert">The app has been hidden. To open it again please dial 8722227 (TRACCAR).</string>
   <string name="error_msg_invalid_url">Please enter a valid http:// or https:// URL</string>
-  <string name="error_invalid_url_summary">Invalid server URL</string>
 </resources>