Executing java file in qt

Question

I'm trying to execute a java file inside qt, here is my java file code:

import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.Context;

public class Main extends AppWidgetProvider {

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager,
                    int[] appWidgetIds) {
            // TODO Auto-generated method stub
            super.onUpdate(context, appWidgetManager, appWidgetIds);
    }
}

The question is how this java file can be called, I'm confused & don't know how to call the function onUpdate, Any ideas ?

Answer 1

To run Java code in your Qt Android application you should use the Qt Android Extras module which contains additional functionality for development on Android.

You can use JNI to call a Java function from C/C++ or callback a C/C++ function from Java.

Let's consider you have a static Java method like :

package com.MyApp;

public class JavaClass
{
    public static int SomeMethod(int n)
    {
        ...
    }
}

First you need to add this to your .pro file :

QT += androidextras

And Include the relevant header file :

#include <QAndroidJniObject>

You can then call a static java function from your C++ code like :

bool retVal = QAndroidJniObject::callStaticMethod<jint>
                        ("com/MyApp/JavaClass" // class name
                        , "SomeMethod" // method name
                        , "(I)I" // signature
                        , val);

For a more detailed explanation you can see this.