QtJniTypes Namespace

Macro Documentation

[since 6.8] Q_DECLARE_JNI_CLASS(Type, JavaSignature)

Declares a C++ type Type in the QtJniTypes namespace that wraps the Java class JavaSignature. The Java class name in JavaSignature needs to be fully qualified, using / as the separator.

Q_DECLARE_JNI_CLASS(File, "java/io/File")
Q_DECLARE_JNI_CLASS(FileWriter, "java/io/FileWriter")

The C++ classes QtJniTypes::File and QtJniTypes::FileWriter are then QJniObject-like types that can be used to instantiate the corresponding Java class, to call methods, and to pass such instances through QJniObject variadic template methods with automatic, compile-time signature deduction.

using namespace QtJniTypes;

File file("path/to/file"); // instantiates the java.io.File type in Java
if (file.callMethod<bool>("createNewFile")) {
    FileWriter writer(file); // instantiates a java.io.FileWriter that operates on file
    writer.callMethod("write", 42);
}

In addition to the QJniObject API, those C++ classes also have a static registerNativeMethods member function that can be used like this:

QtJniTypes::File::registerNativeMethods({
    Q_JNI_NATIVE_METHOD(freeFunction)
});

This macro was introduced in Qt 6.8.

See also Q_DECLARE_JNI_NATIVE_METHOD and Q_JNI_NATIVE_METHOD.

[since 6.8] Q_DECLARE_JNI_NATIVE_METHOD(Method)

Declares the free C or C++ function Method as a native method. The method can later be registered with the JNI framework using QJniEnvironment::registerNativeMethod() with the help of the Q_JNI_NATIVE_METHOD macro.

// C++ side

Q_DECLARE_JNI_CLASS(MyJavaType, "my/java/Type")

static void nativeFunction(JNIEnv *env, jobject thiz, jlong id)
{
    // ...
}
Q_DECLARE_JNI_NATIVE_METHOD(nativeFunction)

Q_DECL_EXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved)
{
    QJniEnvironment env;
    env.registerNativeMethods<QtJniTypes::MyJavaType>({
        Q_JNI_NATIVE_METHOD(nativeFunction)
    });
}

// Java side
public class MyJavaType
{
    native public nativeFunction(long id);
}

This macro was introduced in Qt 6.8.

See also Q_JNI_NATIVE_METHOD and Q_DECLARE_JNI_NATIVE_METHOD_IN_CURRENT_SCOPE.

[since 6.8] Q_DECLARE_JNI_NATIVE_METHOD(Method, JavaName)

This is an overloaded function.

Declares the free C or C++ function Method as a native method that's available in Java as JavaName. The method can later be registered with the JNI framework using QJniEnvironment::registerNativeMethod() with the help of the Q_JNI_NATIVE_METHOD macro.

This macro was introduced in Qt 6.8.

See also Q_JNI_NATIVE_METHOD and Q_DECLARE_JNI_NATIVE_METHOD_IN_CURRENT_SCOPE.

[since 6.8] Q_DECLARE_JNI_NATIVE_METHOD_IN_CURRENT_SCOPE(Method)

Declares the C++ static class member function Method as a native method. The method can later be registered with the JNI framework using QJniEnvironment::registerNativeMethod() with the help of the Q_JNI_NATIVE_SCOPED_METHOD macro.

class NativeHandler
{
    // ...
private:
    static void handleChange(JNIEnv*, jobject, jlong id);
    Q_DECLARE_JNI_NATIVE_METHOD_IN_CURRENT_SCOPE(handleChange)
};

\dots
QJniEnvironment env;
env.registerNativeMethods<QtJniTypes::MyJavaType>({
    Q_JNI_NATIVE_SCOPED_METHOD(handleChange, NativeHandler)
});

This macro was introduced in Qt 6.8.

See also Q_DECLARE_JNI_NATIVE_METHOD and Q_JNI_NATIVE_SCOPED_METHOD.

[since 6.8] Q_DECLARE_JNI_NATIVE_METHOD_IN_CURRENT_SCOPE(Method, JavaName)

This is an overloaded function.

Declares the C++ static class member function Method as a native method that's available in Java as JavaName. The method can later be registered with the JNI framework using QJniEnvironment::registerNativeMethod() with the help of the Q_JNI_NATIVE_METHOD macro.

This macro was introduced in Qt 6.8.

See also Q_DECLARE_JNI_NATIVE_METHOD and Q_JNI_NATIVE_SCOPED_METHOD.

[since 6.8] Q_JNI_NATIVE_METHOD(Method)

Makes the previously declared native method Method available for registration with the JNI framework. Use this macro when registering the method with JNI using QJniEnvironment::registerNativeMethod().

Q_DECL_EXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved)
{
    QJniEnvironment env;
    env.registerNativeMethods<QtJniTypes::MyJavaType>({
        Q_JNI_NATIVE_METHOD(nativeFunction)
    });
}

This macro was introduced in Qt 6.8.

See also Q_DECLARE_JNI_NATIVE_METHOD.

[since 6.8] Q_JNI_NATIVE_SCOPED_METHOD(Method, Scope)

Makes the previously declared native method Method in scope Scope available for registration with the JNI framework. Use this macro when registering the method with JNI using QJniEnvironment::registerNativeMethod().

This macro was introduced in Qt 6.8.

See also Q_JNI_NATIVE_METHOD and Q_DECLARE_JNI_NATIVE_METHOD_IN_CURRENT_SCOPE.