Android: Add findClass() function to the QJNIEnvironmentPrivate class.

The static QJNIEnvironmentPrivate::findClass() function exposes the
cache and the class finding code in qjni.

Change-Id: I42043dc993cf9cace042faf763f2a647ba79d97f
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>
Reviewed-by: BogDan Vatra <bogdan@kde.org>

6 files changed, 110 insertions, 76 deletions

diff --git a/src/corelib/kernel/qjni.cpp b/src/corelib/kernel/qjni.cpp
index 46e7d739fb..173127b063 100644
--- a/src/corelib/kernel/qjni.cpp
+++ b/src/corelib/kernel/qjni.cpp
@@ -75,28 +75,58 @@ static inline bool exceptionCheckAndClear(JNIEnv *env)
 typedef QHash<QString, jclass> JClassHash;
 Q_GLOBAL_STATIC(JClassHash, cachedClasses)
 
-static jclass getCachedClass(JNIEnv *env, const char *className)
+static QString toDotEncodedClassName(const char *className)
+{
+    return QString::fromLatin1(className).replace(QLatin1Char('/'), QLatin1Char('.'));
+}
+
+static jclass getCachedClass(const QString &classDotEnc)
 {
-    jclass clazz = 0;
-    QString classDotEnc = QString::fromLatin1(className).replace(QLatin1Char('/'), QLatin1Char('.'));
     QHash<QString, jclass>::iterator it = cachedClasses->find(classDotEnc);
-    if (it == cachedClasses->end()) {
-        QJNIObjectPrivate classLoader = QtAndroidPrivate::classLoader();
-        if (!classLoader.isValid())
-            return 0;
 
-        QJNIObjectPrivate stringName = QJNIObjectPrivate::fromString(classDotEnc);
-        QJNIObjectPrivate classObject = classLoader.callObjectMethod("loadClass",
-                                                                     "(Ljava/lang/String;)Ljava/lang/Class;",
-                                                                     stringName.object());
+    if (it == cachedClasses->end())
+        return 0;
 
-        if (!exceptionCheckAndClear(env) && classObject.isValid())
-            clazz = static_cast<jclass>(env->NewGlobalRef(classObject.object()));
+    return it.value();
+}
 
-        cachedClasses->insert(classDotEnc, clazz);
-    } else {
-        clazz = it.value();
+static jclass findClass(const char *className, JNIEnv *env)
+{
+    const QString &classDotEnc = toDotEncodedClassName(className);
+    jclass clazz = getCachedClass(classDotEnc);
+    if (clazz != 0)
+        return clazz;
+
+    jclass fclazz = env->FindClass(className);
+    if (!exceptionCheckAndClear(env)) {
+        clazz = static_cast<jclass>(env->NewGlobalRef(fclazz));
+        env->DeleteLocalRef(fclazz);
     }
+
+    cachedClasses->insert(classDotEnc, clazz);
+    return clazz;
+}
+
+static jclass loadClass(const char *className, JNIEnv *env)
+{
+    const QString &classDotEnc = toDotEncodedClassName(className);
+    jclass clazz = getCachedClass(classDotEnc);
+    if (clazz != 0)
+        return clazz;
+
+    QJNIObjectPrivate classLoader = QtAndroidPrivate::classLoader();
+    if (!classLoader.isValid())
+        return 0;
+
+    QJNIObjectPrivate stringName = QJNIObjectPrivate::fromString(classDotEnc);
+    QJNIObjectPrivate classObject = classLoader.callObjectMethod("loadClass",
+                                                                 "(Ljava/lang/String;)Ljava/lang/Class;",
+                                                                 stringName.object());
+
+    if (!exceptionCheckAndClear(env) && classObject.isValid())
+        clazz = static_cast<jclass>(env->NewGlobalRef(classObject.object()));
+
+    cachedClasses->insert(classDotEnc, clazz);
     return clazz;
 }
 
@@ -192,6 +222,18 @@ JNIEnv *QJNIEnvironmentPrivate::operator->()
     return jniEnv;
 }
 
+jclass QJNIEnvironmentPrivate::findClass(const char *className, JNIEnv *env)
+{
+    jclass clazz = 0;
+    if (env != 0)
+        clazz = ::findClass(className, env);
+
+    if (clazz == 0)
+        clazz = loadClass(className, QJNIEnvironmentPrivate());
+
+    return clazz;
+}
+
 QJNIEnvironmentPrivate::operator JNIEnv* () const
 {
     return jniEnv;
@@ -228,7 +270,7 @@ QJNIObjectPrivate::QJNIObjectPrivate(const char *className)
     : d(new QJNIObjectData())
 {
     QJNIEnvironmentPrivate env;
-    d->m_jclass = getCachedClass(env, className);
+    d->m_jclass = loadClass(className, env);
     d->m_own_jclass = false;
     if (d->m_jclass) {
         // get default constructor
@@ -247,7 +289,7 @@ QJNIObjectPrivate::QJNIObjectPrivate(const char *className, const char *sig, ...
     : d(new QJNIObjectData())
 {
     QJNIEnvironmentPrivate env;
-    d->m_jclass = getCachedClass(env, className);
+    d->m_jclass = loadClass(className, env);
     d->m_own_jclass = false;
     if (d->m_jclass) {
         jmethodID constructorId = getCachedMethodID(env, d->m_jclass, "<init>", sig);
@@ -268,7 +310,7 @@ QJNIObjectPrivate::QJNIObjectPrivate(const char *className, const char *sig, va_
     : d(new QJNIObjectData())
 {
     QJNIEnvironmentPrivate env;
-    d->m_jclass = getCachedClass(env, className);
+    d->m_jclass = loadClass(className, env);
     d->m_own_jclass = false;
     if (d->m_jclass) {
         jmethodID constructorId = getCachedMethodID(env, d->m_jclass, "<init>", sig);
@@ -610,7 +652,7 @@ void QJNIObjectPrivate::callStaticMethod<void>(const char *className,
                                                va_list args)
 {
     QJNIEnvironmentPrivate env;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz) {
         jmethodID id = getCachedMethodID(env, clazz, methodName, sig, true);
         if (id) {
@@ -664,7 +706,7 @@ jboolean QJNIObjectPrivate::callStaticMethod<jboolean>(const char *className,
 {
     QJNIEnvironmentPrivate env;
     jboolean res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz) {
         jmethodID id = getCachedMethodID(env, clazz, methodName, sig, true);
         if (id) {
@@ -725,7 +767,7 @@ jbyte QJNIObjectPrivate::callStaticMethod<jbyte>(const char *className,
 {
     QJNIEnvironmentPrivate env;
     jbyte res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz) {
         jmethodID id = getCachedMethodID(env, clazz, methodName, sig, true);
         if (id) {
@@ -786,7 +828,7 @@ jchar QJNIObjectPrivate::callStaticMethod<jchar>(const char *className,
 {
     QJNIEnvironmentPrivate env;
     jchar res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz) {
         jmethodID id = getCachedMethodID(env, clazz, methodName, sig, true);
         if (id) {
@@ -847,7 +889,7 @@ jshort QJNIObjectPrivate::callStaticMethod<jshort>(const char *className,
 {
     QJNIEnvironmentPrivate env;
     jshort res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz) {
         jmethodID id = getCachedMethodID(env, clazz, methodName, sig, true);
         if (id) {
@@ -908,7 +950,7 @@ jint QJNIObjectPrivate::callStaticMethod<jint>(const char *className,
 {
     QJNIEnvironmentPrivate env;
     jint res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz) {
         jmethodID id = getCachedMethodID(env, clazz, methodName, sig, true);
         if (id) {
@@ -969,7 +1011,7 @@ jlong QJNIObjectPrivate::callStaticMethod<jlong>(const char *className,
 {
     QJNIEnvironmentPrivate env;
     jlong res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz) {
         jmethodID id = getCachedMethodID(env, clazz, methodName, sig, true);
         if (id) {
@@ -1030,7 +1072,7 @@ jfloat QJNIObjectPrivate::callStaticMethod<jfloat>(const char *className,
 {
     QJNIEnvironmentPrivate env;
     jfloat res = 0.f;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz) {
         jmethodID id = getCachedMethodID(env, clazz, methodName, sig, true);
         if (id) {
@@ -1091,7 +1133,7 @@ jdouble QJNIObjectPrivate::callStaticMethod<jdouble>(const char *className,
 {
     QJNIEnvironmentPrivate env;
     jdouble res = 0.;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz) {
         jmethodID id = getCachedMethodID(env, clazz, methodName, sig, true);
         if (id) {
@@ -1336,7 +1378,7 @@ QJNIObjectPrivate QJNIObjectPrivate::callStaticObjectMethod(const char *classNam
 {
     QJNIEnvironmentPrivate env;
     jobject res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz) {
         jmethodID id = getCachedMethodID(env, clazz, methodName, sig, true);
         if (id) {
@@ -1507,7 +1549,7 @@ jboolean QJNIObjectPrivate::getStaticField<jboolean>(const char *className, cons
 {
     QJNIEnvironmentPrivate env;
     jboolean res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         res = getStaticField<jboolean>(clazz, fieldName);
 
@@ -1531,7 +1573,7 @@ jbyte QJNIObjectPrivate::getStaticField<jbyte>(const char *className, const char
 {
     QJNIEnvironmentPrivate env;
     jbyte res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         res = getStaticField<jbyte>(clazz, fieldName);
 
@@ -1555,7 +1597,7 @@ jchar QJNIObjectPrivate::getStaticField<jchar>(const char *className, const char
 {
     QJNIEnvironmentPrivate env;
     jchar res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         res = getStaticField<jchar>(clazz, fieldName);
 
@@ -1579,7 +1621,7 @@ jshort QJNIObjectPrivate::getStaticField<jshort>(const char *className, const ch
 {
     QJNIEnvironmentPrivate env;
     jshort res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         res = getStaticField<jshort>(clazz, fieldName);
 
@@ -1603,7 +1645,7 @@ jint QJNIObjectPrivate::getStaticField<jint>(const char *className, const char *
 {
     QJNIEnvironmentPrivate env;
     jint res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         res = getStaticField<jint>(clazz, fieldName);
 
@@ -1627,7 +1669,7 @@ jlong QJNIObjectPrivate::getStaticField<jlong>(const char *className, const char
 {
     QJNIEnvironmentPrivate env;
     jlong res = 0;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         res = getStaticField<jlong>(clazz, fieldName);
 
@@ -1651,7 +1693,7 @@ jfloat QJNIObjectPrivate::getStaticField<jfloat>(const char *className, const ch
 {
     QJNIEnvironmentPrivate env;
     jfloat res = 0.f;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         res = getStaticField<jfloat>(clazz, fieldName);
 
@@ -1675,7 +1717,7 @@ jdouble QJNIObjectPrivate::getStaticField<jdouble>(const char *className, const
 {
     QJNIEnvironmentPrivate env;
     jdouble res = 0.;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         res = getStaticField<jdouble>(clazz, fieldName);
 
@@ -1705,7 +1747,7 @@ QJNIObjectPrivate QJNIObjectPrivate::getStaticObjectField(const char *className,
 {
     QJNIEnvironmentPrivate env;
     QJNIObjectPrivate res;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         res = getStaticObjectField(clazz, fieldName, sig);
 
@@ -1941,7 +1983,7 @@ void QJNIObjectPrivate::setStaticField<jboolean>(const char *className,
                                                  jboolean value)
 {
     QJNIEnvironmentPrivate env;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         setStaticField<jboolean>(clazz, fieldName, value);
 }
@@ -1963,7 +2005,7 @@ void QJNIObjectPrivate::setStaticField<jbyte>(const char *className,
                                               jbyte value)
 {
     QJNIEnvironmentPrivate env;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         setStaticField<jbyte>(clazz, fieldName, value);
 }
@@ -1985,7 +2027,7 @@ void QJNIObjectPrivate::setStaticField<jchar>(const char *className,
                                               jchar value)
 {
     QJNIEnvironmentPrivate env;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         setStaticField<jchar>(clazz, fieldName, value);
 }
@@ -2007,7 +2049,7 @@ void QJNIObjectPrivate::setStaticField<jshort>(const char *className,
                                                jshort value)
 {
     QJNIEnvironmentPrivate env;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         setStaticField<jshort>(clazz, fieldName, value);
 }
@@ -2029,7 +2071,7 @@ void QJNIObjectPrivate::setStaticField<jint>(const char *className,
                                              jint value)
 {
     QJNIEnvironmentPrivate env;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         setStaticField<jint>(clazz, fieldName, value);
 }
@@ -2051,7 +2093,7 @@ void QJNIObjectPrivate::setStaticField<jlong>(const char *className,
                                               jlong value)
 {
     QJNIEnvironmentPrivate env;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         setStaticField<jlong>(clazz, fieldName, value);
 }
@@ -2073,7 +2115,7 @@ void QJNIObjectPrivate::setStaticField<jfloat>(const char *className,
                                                jfloat value)
 {
     QJNIEnvironmentPrivate env;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         setStaticField<jfloat>(clazz, fieldName, value);
 }
@@ -2095,7 +2137,7 @@ void QJNIObjectPrivate::setStaticField<jdouble>(const char *className,
                                                 jdouble value)
 {
     QJNIEnvironmentPrivate env;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         setStaticField<jdouble>(clazz, fieldName, value);
 }
@@ -2119,7 +2161,7 @@ void QJNIObjectPrivate::setStaticField<jobject>(const char *className,
                                                 jobject value)
 {
     QJNIEnvironmentPrivate env;
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     if (clazz)
         setStaticField<jobject>(clazz, fieldName, sig, value);
 }
@@ -2150,7 +2192,7 @@ bool QJNIObjectPrivate::isClassAvailable(const char *className)
     if (!env)
         return false;
 
-    jclass clazz = getCachedClass(env, className);
+    jclass clazz = loadClass(className, env);
     return (clazz != 0);
 }
 
diff --git a/src/corelib/kernel/qjni_p.h b/src/corelib/kernel/qjni_p.h
index 528872aa9b..19f2cf7601 100644
--- a/src/corelib/kernel/qjni_p.h
+++ b/src/corelib/kernel/qjni_p.h
@@ -58,6 +58,7 @@ public:
     ~QJNIEnvironmentPrivate();
     JNIEnv *operator->();
     operator JNIEnv*() const;
+    static jclass findClass(const char *className, JNIEnv *env = 0);
 
 private:
     friend class QAndroidJniEnvironment;
diff --git a/src/plugins/platforms/android/androidjnimain.cpp b/src/plugins/platforms/android/androidjnimain.cpp
index 17a587b333..e068a43241 100644
--- a/src/plugins/platforms/android/androidjnimain.cpp
+++ b/src/plugins/platforms/android/androidjnimain.cpp
@@ -162,14 +162,6 @@ namespace QtAndroid
         return m_javaVM;
     }
 
-    jclass findClass(const QString &className, JNIEnv *env)
-    {
-        return static_cast<jclass>(env->CallObjectMethod(m_classLoaderObject,
-                                                         m_loadClassMethodID,
-                                                         env->NewString(reinterpret_cast<const jchar *>(className.constData()),
-                                                                        jsize(className.length()))));
-    }
-
     AAssetManager *assetManager()
     {
         return m_assetManager;
diff --git a/src/plugins/platforms/android/androidjnimain.h b/src/plugins/platforms/android/androidjnimain.h
index 3e226b13c2..7f762c8108 100644
--- a/src/plugins/platforms/android/androidjnimain.h
+++ b/src/plugins/platforms/android/androidjnimain.h
@@ -70,7 +70,6 @@ namespace QtAndroid
     int desktopHeightPixels();
     double scaledDensity();
     JavaVM *javaVM();
-    jclass findClass(const QString &className, JNIEnv *env);
     AAssetManager *assetManager();
     jclass applicationClass();
     jobject activity();
diff --git a/src/plugins/platforms/android/qandroidinputcontext.cpp b/src/plugins/platforms/android/qandroidinputcontext.cpp
index 5ff13902ac..abda72e636 100644
--- a/src/plugins/platforms/android/qandroidinputcontext.cpp
+++ b/src/plugins/platforms/android/qandroidinputcontext.cpp
@@ -45,6 +45,7 @@
 #include <qthread.h>
 #include <qinputmethod.h>
 #include <qwindow.h>
+#include <QtCore/private/qjni_p.h>
 
 #include <QTextCharFormat>
 
@@ -53,8 +54,8 @@
 QT_BEGIN_NAMESPACE
 
 static QAndroidInputContext *m_androidInputContext = 0;
-static char const *const QtNativeInputConnectionClassName = "org.qtproject.qt5.android.QtNativeInputConnection";
-static char const *const QtExtractedTextClassName = "org.qtproject.qt5.android.QtExtractedText";
+static char const *const QtNativeInputConnectionClassName = "org/qtproject/qt5/android/QtNativeInputConnection";
+static char const *const QtExtractedTextClassName = "org/qtproject/qt5/android/QtExtractedText";
 static jclass m_extractedTextClass = 0;
 static jmethodID m_classConstructorMethodID = 0;
 static jfieldID m_partialEndOffsetFieldID = 0;
@@ -334,11 +335,7 @@ static JNINativeMethod methods[] = {
 QAndroidInputContext::QAndroidInputContext()
     : QPlatformInputContext(), m_composingTextStart(-1), m_blockUpdateSelection(false),  m_batchEditNestingLevel(0), m_focusObject(0)
 {
-    QtAndroid::AttachedJNIEnv env;
-    if (!env.jniEnv)
-        return;
-
-    jclass clazz = QtAndroid::findClass(QtNativeInputConnectionClassName, env.jniEnv);
+    jclass clazz = QJNIEnvironmentPrivate::findClass(QtNativeInputConnectionClassName);
     if (clazz == NULL) {
         qCritical() << "Native registration unable to find class '"
                     << QtNativeInputConnectionClassName
@@ -346,14 +343,15 @@ QAndroidInputContext::QAndroidInputContext()
         return;
     }
 
-    if (env.jniEnv->RegisterNatives(clazz, methods, sizeof(methods) / sizeof(methods[0])) < 0) {
+    QJNIEnvironmentPrivate env;
+    if (env->RegisterNatives(clazz, methods, sizeof(methods) / sizeof(methods[0])) < 0) {
         qCritical() << "RegisterNatives failed for '"
                     << QtNativeInputConnectionClassName
                     << "'";
         return;
     }
 
-    clazz = QtAndroid::findClass(QtExtractedTextClassName, env.jniEnv);
+    clazz = QJNIEnvironmentPrivate::findClass(QtExtractedTextClassName);
     if (clazz == NULL) {
         qCritical() << "Native registration unable to find class '"
                     << QtExtractedTextClassName
@@ -361,44 +359,44 @@ QAndroidInputContext::QAndroidInputContext()
         return;
     }
 
-    m_extractedTextClass = static_cast<jclass>(env.jniEnv->NewGlobalRef(clazz));
-    m_classConstructorMethodID = env.jniEnv->GetMethodID(m_extractedTextClass, "<init>", "()V");
+    m_extractedTextClass = static_cast<jclass>(env->NewGlobalRef(clazz));
+    m_classConstructorMethodID = env->GetMethodID(m_extractedTextClass, "<init>", "()V");
     if (m_classConstructorMethodID == NULL) {
         qCritical() << "GetMethodID failed";
         return;
     }
 
-    m_partialEndOffsetFieldID = env.jniEnv->GetFieldID(m_extractedTextClass, "partialEndOffset", "I");
+    m_partialEndOffsetFieldID = env->GetFieldID(m_extractedTextClass, "partialEndOffset", "I");
     if (m_partialEndOffsetFieldID == NULL) {
         qCritical() << "Can't find field partialEndOffset";
         return;
     }
 
-    m_partialStartOffsetFieldID = env.jniEnv->GetFieldID(m_extractedTextClass, "partialStartOffset", "I");
+    m_partialStartOffsetFieldID = env->GetFieldID(m_extractedTextClass, "partialStartOffset", "I");
     if (m_partialStartOffsetFieldID == NULL) {
         qCritical() << "Can't find field partialStartOffset";
         return;
     }
 
-    m_selectionEndFieldID = env.jniEnv->GetFieldID(m_extractedTextClass, "selectionEnd", "I");
+    m_selectionEndFieldID = env->GetFieldID(m_extractedTextClass, "selectionEnd", "I");
     if (m_selectionEndFieldID == NULL) {
         qCritical() << "Can't find field selectionEnd";
         return;
     }
 
-    m_selectionStartFieldID = env.jniEnv->GetFieldID(m_extractedTextClass, "selectionStart", "I");
+    m_selectionStartFieldID = env->GetFieldID(m_extractedTextClass, "selectionStart", "I");
     if (m_selectionStartFieldID == NULL) {
         qCritical() << "Can't find field selectionStart";
         return;
     }
 
-    m_startOffsetFieldID = env.jniEnv->GetFieldID(m_extractedTextClass, "startOffset", "I");
+    m_startOffsetFieldID = env->GetFieldID(m_extractedTextClass, "startOffset", "I");
     if (m_startOffsetFieldID == NULL) {
         qCritical() << "Can't find field startOffset";
         return;
     }
 
-    m_textFieldID = env.jniEnv->GetFieldID(m_extractedTextClass, "text", "Ljava/lang/String;");
+    m_textFieldID = env->GetFieldID(m_extractedTextClass, "text", "Ljava/lang/String;");
     if (m_textFieldID == NULL) {
         qCritical() << "Can't find field text";
         return;
diff --git a/src/plugins/platforms/android/qandroidplatformdialoghelpers.cpp b/src/plugins/platforms/android/qandroidplatformdialoghelpers.cpp
index 5f2a877ed3..2ea4c90324 100644
--- a/src/plugins/platforms/android/qandroidplatformdialoghelpers.cpp
+++ b/src/plugins/platforms/android/qandroidplatformdialoghelpers.cpp
@@ -44,6 +44,8 @@ QT_BEGIN_NAMESPACE
 namespace QtAndroidDialogHelpers {
 static jclass g_messageDialogHelperClass = 0;
 
+static const char QtMessageHandlerHelperClassName[] = "org/qtproject/qt5/android/QtMessageDialogHelper";
+
 QAndroidPlatformMessageDialogHelper::QAndroidPlatformMessageDialogHelper()
     :m_buttonId(-1)
     ,m_javaMessageDialog(g_messageDialogHelperClass, "(Landroid/app/Activity;)V", QtAndroid::activity())
@@ -148,10 +150,10 @@ static JNINativeMethod methods[] = {
 
 bool registerNatives(JNIEnv *env)
 {
-    jclass clazz = QtAndroid::findClass("org.qtproject.qt5.android.QtMessageDialogHelper", env);
+    jclass clazz = QJNIEnvironmentPrivate::findClass(QtMessageHandlerHelperClassName, env);
     if (!clazz) {
         __android_log_print(ANDROID_LOG_FATAL, QtAndroid::qtTagText(), QtAndroid::classErrorMsgFmt()
-                            , "org/qtproject/qt5/android/QtMessageDialogHelper");
+                            , QtMessageHandlerHelperClassName);
         return false;
     }
     g_messageDialogHelperClass = static_cast<jclass>(env->NewGlobalRef(clazz));