[android] Closed #472 - get system language

@TODO add dynamic language change support, now application should be restarted to switch language used for the map

android/jni/Android.mk

@@ -36,6 +36,7 @@ LOCAL_SRC_FILES := \
 	com/mapswithme/maps/Lifecycle.cpp \
 	com/mapswithme/platform/Platform.cpp \
 	com/mapswithme/platform/HttpThread.cpp \
+	com/mapswithme/platform/Language.cpp \
 	com/mapswithme/jni/jni_thread.cpp \
 	com/mapswithme/jni/jni_method.cpp \
 	nv_thread/nv_thread.cpp \

android/jni/com/mapswithme/platform/Language.cpp

@@ -0,0 +1,47 @@
+#include <jni.h>
+
+#include "../../../../../base/assert.hpp"
+#include "../../../../../base/logging.hpp"
+
+#include "../../../../../std/string.hpp"
+
+/// Defined and initialized in MWMActivity.cpp
+extern JavaVM * g_jvm;
+
+#define DEFAULT_LANG "en"
+
+/// This function is called from native c++ code
+string GetAndroidSystemLanguage()
+{
+  JNIEnv * env = 0;
+  if (!g_jvm || g_jvm->AttachCurrentThread(&env, 0) || !env)
+  {
+    LOG(LWARNING, ("Can't attach thread"));
+    return DEFAULT_LANG;
+  }
+
+  jclass localeClass = env->FindClass("java/util/Locale");
+  ASSERT(localeClass, ("Can't find java class java/util/Locale"));
+
+  jmethodID localeGetDefaultId = env->GetStaticMethodID(localeClass, "getDefault", "()Ljava/util/Locale;");
+  ASSERT(localeGetDefaultId, ("Can't find static java/util/Locale.getDefault() method"));
+
+  jobject localeInstance = env->CallStaticObjectMethod(localeClass, localeGetDefaultId);
+  ASSERT(localeInstance, ("Locale.getDefault() returned NULL"));
+
+  jmethodID localeGetLanguageId = env->GetMethodID(localeClass, "getLanguage", "()Ljava/lang/String;");
+  ASSERT(localeGetLanguageId, ("Can't find java/util/Locale.getLanguage() method"));
+
+  jstring langString = (jstring)env->CallObjectMethod(localeInstance, localeGetLanguageId);
+  ASSERT(langString, ("Locale.getLanguage() returned NULL"));
+
+  char const * langUtf8 = env->GetStringUTFChars(langString, 0);
+  string result(DEFAULT_LANG);
+  if (langUtf8 != 0)
+  {
+    result = langUtf8;
+    env->ReleaseStringUTFChars(langString, langUtf8);
+  }
+  g_jvm->DetachCurrentThread();
+  return result;
+}

android/src/com/mapswithme/maps/MWMActivity.java

@@ -146,15 +146,6 @@ public class MWMActivity extends NvEventQueueActivity implements
     startActivity(new Intent(this, DownloadUI.class));
   }
 
-  private void setupLanguages()
-  {
-    /*
-     * Log.d(TAG, "Default Language : " + Locale.getDefault().getLanguage());
-     * for (Locale l : Locale.getAvailableLocales()) Log.d(TAG, l.getLanguage()
-     * + " : " + l.getVariant() + " : " + l.toString());
-     */
-  }
-
   @Override
   public void onCreate(Bundle savedInstanceState)
   {
@@ -174,8 +165,6 @@ public class MWMActivity extends NvEventQueueActivity implements
     
     nativeInit(metrics.densityDpi, getAppBundlePath(), extStoragePath, getTmpPath(), extTmpPath, getSettingsPath());
 
-    setupLanguages();
-
     checkMeasurementSystem();
 
     m_timer = new VideoTimer();

platform/preferred_languages.cpp

@@ -20,7 +20,8 @@
   #include "../std/cstdlib.hpp"
 
 #elif defined(OMIM_OS_ANDROID)
-  /// @TODO
+  /// Body for this function is inside android/jni sources
+  string GetAndroidSystemLanguage();
 
 #else
   #error "Define language preferences for your platform"
@@ -155,7 +156,7 @@ void SystemPreferredLanguages(vector<string> & languages)
     languages.push_back(p);
 
 #elif defined(OMIM_OS_ANDROID)
-  /// @TODO
+  languages.push_back(GetAndroidSystemLanguage());
 
 #else
   #error "Define language preferences for your platform"