Added functionality to the dropdown in settings. Language preference is stored in the sharedPreferences

app/src/main/java/com/a1/nextlocation/MainActivity.java

@@ -5,6 +5,9 @@ import androidx.appcompat.app.AppCompatActivity;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentTransaction;
 
+import android.app.Activity;
+import android.content.SharedPreferences;
+import android.content.res.Configuration;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.MenuItem;
@@ -25,6 +28,7 @@ import com.google.android.material.bottomnavigation.BottomNavigationView;
 
 import java.io.File;
 import java.util.Arrays;
+import java.util.Locale;
 
 public class MainActivity extends AppCompatActivity {
     private static final String TAG = MainActivity.class.getName();
@@ -54,9 +58,33 @@ public class MainActivity extends AppCompatActivity {
         RouteListManager.INSTANCE.setContext(this);
         RouteListManager.INSTANCE.load();
 
+        // initialize saved language from sharedPreferences
+        setLocale(loadLocale());
+
         getSupportFragmentManager().beginTransaction().replace(R.id.fragment_layout, new HomeFragment()).commit();
     }
 
+    /**
+     * loads the saved language from SharedPreferences
+     * @return the language as string
+     */
+    private String loadLocale(){
+        SharedPreferences sharedPreferences = getSharedPreferences("Settings", Activity.MODE_PRIVATE);
+        return sharedPreferences.getString("Language", "");
+    }
+
+    /**
+     * sets the language of the application to the desired one
+     * @param language the desired language
+     */
+    private void setLocale(String language){
+        Locale locale = new Locale(language);
+        Locale.setDefault(locale);
+        Configuration configuration = new Configuration();
+        configuration.setLocale(locale);
+        getBaseContext().getResources().getConfiguration().updateFrom(configuration);
+    }
+
 
     private BottomNavigationView.OnNavigationItemSelectedListener navListener = item -> {
         Fragment selectedFragment = null;

app/src/main/java/com/a1/nextlocation/fragments/SettingsFragment.java

@@ -1,5 +1,8 @@
 package com.a1.nextlocation.fragments;
 
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.content.res.Configuration;
 import android.os.Bundle;
 
 import androidx.annotation.NonNull;
@@ -9,36 +12,102 @@ import androidx.fragment.app.Fragment;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
+import android.widget.AdapterView;
 import android.widget.ArrayAdapter;
 import android.widget.Spinner;
 
 import com.a1.nextlocation.MainActivity;
 import com.a1.nextlocation.R;
 
+import java.util.Locale;
+
 public class SettingsFragment extends Fragment {
 
+    private SharedPreferences.Editor editor;
+    private String language;
+
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        editor = getContext().getSharedPreferences("Settings", Context.MODE_PRIVATE).edit();
     }
 
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container,
                              Bundle savedInstanceState) {
-        
-        return inflater.inflate(R.layout.fragment_settings, container, false);
+
+        View view = inflater.inflate(R.layout.fragment_settings, container, false);
+
+        initializeLanguageDropdown(view);
+
+        return view;
     }
 
-    @Override
-    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
-        super.onViewCreated(view, savedInstanceState);
-
-        // Inflate the layout for this fragment
-        Spinner dropdown = view.findViewById(R.id.dropdown_menu_Settings);
-
+    private void initializeLanguageDropdown(View view) {
+        Spinner languageDropdown = view.findViewById(R.id.dropdown_menu_Settings);
         String[] items = new String[]{"Nederlands", "Engels", "Chinees"};
         ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(getActivity(), android.R.layout.simple_spinner_dropdown_item, items);
+        languageDropdown.setAdapter(arrayAdapter);
 
-        dropdown.setAdapter(arrayAdapter);
+        // set the language dropdown on the currently selected language stored in the sharedPreferences
+        languageDropdown.setSelection(languageToDropdownPosition(getContext().getSharedPreferences("Settings", Context.MODE_PRIVATE).getString("Language", "")));
+
+        languageDropdown.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
+            @Override
+            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                setLocale(dropdownPositionToLanguage(position));
+            }
+
+            @Override
+            public void onNothingSelected(AdapterView<?> parent) {
+
+            }
+        });
+    }
+
+    /**
+     * converts the languageDropdown position to the belonging language
+     * @param position desired position to convert
+     * @return the language belonging to the position of the languageDropdown
+     */
+    private String dropdownPositionToLanguage(int position) {
+        switch (position){
+            case 0:
+                return "nl";
+            case 1:
+                return "en";
+            default:
+                return "";
+        }
+    }
+
+    /**
+     * converts language to the languageDropdown position
+     * @param language desired language to convert
+     * @return the position of the language in the languageDropdown
+     */
+    private int languageToDropdownPosition(String language) {
+        switch (language) {
+            case "nl":
+                return 0;
+            case "en":
+                return 1;
+            default:
+                return 1;
+        }
+    }
+
+    /**
+     * changes the current language to the desired language and saves this setting in SharedPreferences
+     * @param language the desired language to translate to
+     */
+    private void setLocale(String language){
+        Locale locale = new Locale(language);
+        Locale.setDefault(locale);
+        Configuration config = new Configuration();
+        config.setLocale(locale);
+        getContext().getResources().getConfiguration().updateFrom(config);
+        editor.putString("Language", language);
+        editor.apply();
     }
 }