QJniObject: Add template overloads for get/setStaticField

Allow specifying the Java class on which to set/get the field via its
corresponding C++ type, removing the need to explicitly provide the
Java type string.

Those were missing from a085a14d76553ebd1fa4a4a11a27110ee544a531, which
was noticed when porting QtConnectivity over to the new template APIs.

Pick-to: 6.4
Change-Id: I8f324c9fcc486b4c6c2f2b9051f7eca0cbec0e91
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>

src/corelib/kernel/qjniobject.cpp

@@ -1230,6 +1230,14 @@ QJniObject QJniObject::callStaticObjectMethod(jclass clazz, jmethodID methodId,
     Retrieves the value from the static field \a fieldName on \a clazz.
 */
 
+/*!
+    \fn template <typename Klass, typename T> auto QJniObject::getStaticField(const char *fieldName)
+
+    Retrieves the value from the static field \a fieldName for the class \c Klass.
+
+    \c Klass needs to be a C++ type with a registered type mapping to a Java type.
+*/
+
 /*!
     \fn template <typename T> void QJniObject::setStaticField(const char *className, const char *fieldName, T value)
 
@@ -1242,6 +1250,14 @@ QJniObject QJniObject::callStaticObjectMethod(jclass clazz, jmethodID methodId,
     Sets the static field \a fieldName of the class \a clazz to \a value.
 */
 
+/*!
+    \fn template <typename Klass, typename T> auto QJniObject::setStaticField(const char *fieldName, T value)
+
+    Sets the static field \a fieldName of the class \c Klass to \a value.
+
+    \c Klass needs to be a C++ type with a registered type mapping to a Java type.
+*/
+
 /*!
     \fn QJniObject QJniObject::getStaticObjectField(const char *className, const char *fieldName, const char *signature)
 

src/corelib/kernel/qjniobject.h

@@ -258,6 +258,12 @@ public:
         }
     }
 
+    template <typename Klass, typename T>
+    static auto getStaticField(const char *fieldName)
+    {
+        return getStaticField<T>(QtJniTypes::className<Klass>(), fieldName);
+    }
+
     template <typename T>
     QJniObject getObjectField(const char *fieldName) const
     {
@@ -380,6 +386,12 @@ public:
         }
     }
 
+    template <typename Klass, typename T>
+    static void setStaticField(const char *fieldName, T value)
+    {
+        setStaticField(QtJniTypes::className<Klass>(), fieldName, value);
+    }
+
     static QJniObject fromString(const QString &string);
     QString toString() const;
 

tests/auto/corelib/kernel/qjniobject/tst_qjniobject.cpp

@@ -9,6 +9,7 @@
 #include <QtTest>
 
 static const char testClassName[] = "org/qtproject/qt/android/testdatapackage/QtJniObjectTestClass";
+Q_DECLARE_JNI_CLASS(QtJniObjectTestClass, testClassName)
 
 static const jbyte A_BYTE_VALUE = 127;
 static const jshort A_SHORT_VALUE = 32767;
@@ -1035,6 +1036,12 @@ void setStaticField(const char *fieldName, T testValue)
 
     T res = QJniObject::getStaticField<T>(testClassName, fieldName);
     QCOMPARE(res, testValue);
+
+    // use template overload to reset to default
+    T defaultValue = {};
+    QJniObject::setStaticField<QtJniTypes::QtJniObjectTestClass, T>(fieldName, defaultValue);
+    res = QJniObject::getStaticField<QtJniTypes::QtJniObjectTestClass, T>(fieldName);
+    QCOMPARE(res, defaultValue);
 }
 
 void tst_QJniObject::setStaticIntField()