1 immutability of results

library/src/main/java/com/tomaytotomato/LocationService.java

@@ -10,12 +10,15 @@
 import com.tomaytotomato.usecase.FindCity;
 import com.tomaytotomato.usecase.FindCountry;
 import com.tomaytotomato.usecase.FindState;
+
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 /**
  * This class provides simple lookups for Country, State and City information.
@@ -148,7 +151,7 @@ public Optional<Country> findCountryByISO3Code(String iso3Code) {
   }
 
   public List<Country> findAllCountries() {
-    return countries;
+    return Collections.unmodifiableList(countries);
   }
 
   /**
@@ -174,9 +177,9 @@ public List<Country> findAllCountriesByStateName(String stateName) {
       return stateNameToStatesMap.get(stateName).stream().map(state -> findCountryById(state.getCountryId()))
           .filter(Optional::isPresent)
           .map(Optional::get)
-          .toList();
+          .collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
     } else {
-      return new ArrayList<>();
+      return Collections.emptyList();
     }
   }
 
@@ -197,9 +200,9 @@ public List<State> findAllStatesByStateName(String stateName) {
     }
     stateName = textNormaliser.normalise(stateName);
     if (stateNameToStatesMap.containsKey(stateName)) {
-      return stateNameToStatesMap.get(stateName);
+      return Collections.unmodifiableList(stateNameToStatesMap.get(stateName));
     } else {
-      return new ArrayList<>();
+      return Collections.emptyList();
     }
   }
 
@@ -210,9 +213,9 @@ public List<State> findAllStatesByStateCode(String stateCode) {
     }
     stateCode = textNormaliser.normalise(stateCode);
     if (stateCodeToStatesMap.containsKey(stateCode)) {
-      return stateCodeToStatesMap.get(stateCode);
+      return Collections.unmodifiableList(stateCodeToStatesMap.get(stateCode));
     } else {
-      return new ArrayList<>();
+      return Collections.emptyList();
     }
   }
 
@@ -226,7 +229,8 @@ public Optional<City> findCityById(Integer id) {
 
   @Override
   public List<City> findAllCities() {
-    return cityNameToCitiesMap.values().stream().flatMap(List::stream).toList();
+    return cityNameToCitiesMap.values().stream().flatMap(List::stream).collect(
+        Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
   }
 
   @Override
@@ -236,9 +240,9 @@ public List<City> findAllCitiesByCityName(String cityName) {
     }
     cityName = textNormaliser.normalise(cityName);
     if (cityNameToCitiesMap.containsKey(cityName)) {
-      return cityNameToCitiesMap.get(cityName);
+      return Collections.unmodifiableList(cityNameToCitiesMap.get(cityName));
     } else {
-      return new ArrayList<>();
+      return Collections.emptyList();
     }
   }
 }

library/src/main/java/com/tomaytotomato/SearchLocationService.java

@@ -25,7 +25,6 @@
 
 /**
  * Provides search functionality to find a Country, State or City based on text input
- *
  */
 public class SearchLocationService implements SearchLocation {