Android: Modernize the QAndroidSystemLocale implementation

Declare the Java classes we use, and use the modern template API to
call methods and access fields. Make use of the implicit conversion to
QString.

As a drive-by, limit the write-locking of the mutex that protects the
data to the write access to that data. The rest of the function operates
on objects on the stack.

Change-Id: I3991c3804339f005aaf8e81a697363ab39306a2f
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>

1 files changed, 22 insertions, 19 deletions

diff --git a/src/plugins/platforms/android/qandroidsystemlocale.cpp b/src/plugins/platforms/android/qandroidsystemlocale.cpp
index ab1ece7d39..d1e9dd81c2 100644
--- a/src/plugins/platforms/android/qandroidsystemlocale.cpp
+++ b/src/plugins/platforms/android/qandroidsystemlocale.cpp
@@ -12,28 +12,34 @@
 
 QT_BEGIN_NAMESPACE
 
+Q_DECLARE_JNI_CLASS(Locale, "java/util/Locale")
+Q_DECLARE_JNI_CLASS(Resources, "android/content/res/Resources")
+Q_DECLARE_JNI_CLASS(Configuration, "android/content/res/Configuration")
+Q_DECLARE_JNI_CLASS(LocaleList, "android/os/LocaleList")
+
+using namespace QtJniTypes;
+
 QAndroidSystemLocale::QAndroidSystemLocale() : m_locale(QLocale::C)
 {
 }
 
 void QAndroidSystemLocale::getLocaleFromJava() const
 {
-    QWriteLocker locker(&m_lock);
-
-    QJniObject javaLocaleObject;
-    const QJniObject javaContext = QtAndroidPrivate::context();
-    if (javaContext.isValid()) {
-        QJniObject resources = javaContext.callObjectMethod("getResources", "()Landroid/content/res/Resources;");
-        QJniObject configuration = resources.callObjectMethod("getConfiguration", "()Landroid/content/res/Configuration;");
-
-        javaLocaleObject = configuration.getObjectField("locale", "Ljava/util/Locale;");
-    } else {
-        javaLocaleObject = QJniObject::callStaticObjectMethod("java/util/Locale", "getDefault", "()Ljava/util/Locale;");
-    }
+    const Locale javaLocaleObject = []{
+        const QJniObject javaContext = QtAndroidPrivate::context();
+        if (javaContext.isValid()) {
+            const QJniObject resources = javaContext.callMethod<Resources>("getResources");
+            const QJniObject configuration = resources.callMethod<Configuration>("getConfiguration");
+            return configuration.getField<Locale>("locale");
+        } else {
+            return Locale::callStaticMethod<Locale>("getDefault");
+        }
+    }();
 
-    QString languageCode = javaLocaleObject.callObjectMethod("getLanguage", "()Ljava/lang/String;").toString();
-    QString countryCode = javaLocaleObject.callObjectMethod("getCountry", "()Ljava/lang/String;").toString();
+    const QString languageCode = javaLocaleObject.callMethod<QString>("getLanguage");
+    const QString countryCode = javaLocaleObject.callMethod<QString>("getCountry");
 
+    QWriteLocker locker(&m_lock);
     m_locale = QLocale(languageCode + u'_' + countryCode);
 }
 
@@ -140,12 +146,9 @@ QVariant QAndroidSystemLocale::query(QueryType type, QVariant in) const
         Q_ASSERT_X(false, Q_FUNC_INFO, "This can't happen.");
     case UILanguages: {
         if (QtAndroidPrivate::androidSdkVersion() >= 24) {
-            QJniObject localeListObject =
-                QJniObject::callStaticObjectMethod("android/os/LocaleList", "getDefault",
-                                                   "()Landroid/os/LocaleList;");
+            LocaleList localeListObject = LocaleList::callStaticMethod<LocaleList>("getDefault");
             if (localeListObject.isValid()) {
-                QString lang = localeListObject.callObjectMethod("toLanguageTags",
-                                                                 "()Ljava/lang/String;").toString();
+                QString lang = localeListObject.callMethod<QString>("toLanguageTags");
                 // Some devices return with it enclosed in []'s so check if both exists before
                 // removing to ensure it is formatted correctly
                 if (lang.startsWith(QChar('[')) && lang.endsWith(QChar(']')))