title: How to call non-static Java method in QtActivity from C++/Qt
body: <p>Eskil Abrahamsen Blomfeldt has a post on his blog showing how to call QtActivity/(HangmanActivity) static Java methods from C++ <a href="http://blog.qt.digia.com/blog/2013/12/12/implementing-in-app-purchase-on-android/" rel="nofollow">here</a>.</p>
  
  <p>He mentions that he only uses static methods because this is easier (indeed) and nothing more is needed in his example. Quote:</p>
  
  <blockquote>
    <p>In my game, the Activity is a singleton, so I store a static reference
    to the object in the constructor. (My C++ Data class has the same
    logic. I’m doing this so that I can facilitate the communication
    between the Java and the C++ code using static methods. For a more
    complex example, it’s also possible to store references and pointers
    in each C++ and Java object that maps it to its equivalent in the
    other language, but that is not necessary in this game.)</p>
  </blockquote>
  
  <p>Calling the static method works. Calling the non-static method does not work(function is never entered). If I call the non-static method connectBluetooth() in onCreate() it works. Is there a way to be able to call and not have the non-static method in onCreate()?</p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>I figured I'll add some code. I have extended the QtActivity class:</p>
  
  <pre><code>package org.qtproject.qt5.android.bindings;
  
  import org.qtproject.qt5.android.bindings.QtApplication;
  import org.qtproject.qt5.android.bindings.QtActivity;
  import android.bluetooth.BluetoothAdapter;
  import android.content.Intent;
  import android.os.Bundle;
  import android.util.Log;
  import java.lang.String;
  
  public class MyActivity extends QtActivity
  {
      private BluetoothAdapter bluetoothAdapter;
      private static final int ENABLE_BLUETOOTH_REQUEST = 1;
  
          public MyActivity()
          {
              Log.d(QtApplication.QtTAG, "MyActivity constructor called");
          }
  
          @Override
          public void onCreate(Bundle savedInstanceState)
          {
              super.onCreate(savedInstanceState);
          }
  
          @Override
          public void onDestroy()
          {
              super.onDestroy();
          }
  
      @Override
          protected void onActivityResult(int requestCode, int resultCode, Intent data)
      {
                  Log.d(QtApplication.QtTAG, "onActivityResult entered");
          if(requestCode == 1)
          {
              if(requestCode == 1)
              {
                  if(resultCode == RESULT_OK)
                  {
                                          Log.d(QtApplication.QtTAG, "User accepted to enable Bluetooth");
                  }
                  else if(resultCode == RESULT_CANCELED)
                  {
                                          Log.d(QtApplication.QtTAG, "User declined to enable Bluetooth");
                  }
              }
          }
      }
  
          public void connectBluetooth()
          {
              Log.d(QtApplication.QtTAG, "connectBluetooth() entered");
              bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
              if(bluetoothAdapter == null)
              {
                  Log.d(QtApplication.QtTAG, "Bluetooth adapter is not found");
                  return;
              }
  
              if(!bluetoothAdapter.isEnabled())
              {
                  Log.d(QtApplication.QtTAG, "Bluetooth is off");
                  Intent enableBluetoothIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                  startActivityForResult(enableBluetoothIntent, ENABLE_BLUETOOTH_REQUEST);
              }
          }
  
          public static void test()
          {
              Log.d(QtApplication.QtTAG, "Static Test OK!");
          }
  }
  </code></pre>
  
  <p>and I try to call these methods from this C++ class:</p>
  
  <pre><code>#include "bluetooth.h"
  #include &lt;QtAndroidExtras&gt;
  #include &lt;QDebug&gt;
  
  Bluetooth::Bluetooth(QObject *parent) :
      QObject(parent)
  {
  }
  
  void Bluetooth::connect()
  {
      //Test static call
      QAndroidJniObject::callStaticMethod&lt;void&gt;("org/qtproject/qt5/android/bindings/MyActivity", "test");
  
  
      //Test non-static call
      //Line below creates a new object and is a subclass of QtActivity.
      bluetooth = new QAndroidJniObject("org/qtproject/qt5/android/bindings/MyActivity");
  
      if(!bluetooth-&gt;isValid())
      {
          qDebug() &lt;&lt; "bluetooth is an invalid java object";
          return;
      }
  
      bluetooth-&gt;callMethod&lt;void&gt;("connectBluetooth");
  }
  </code></pre>
  
  <p><strong>EDIT:</strong>
  The part of the program I am most uncertain about is the AndroidManifest.xml. Maybe there is something here that can explain this behaviour?</p>
  
  <pre><code>&lt;?xml version='1.0' encoding='utf-8'?&gt;
  &lt;manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" package="org.qtproject.example.AndroidTest" android:versionName="1.0" android:installLocation="auto"&gt;
      &lt;application android:label="@string/app_name" android:name="org.qtproject.qt5.android.bindings.QtApplication"&gt;
          &lt;activity android:configChanges="orientation|uiMode|screenLayout|screenSize|smallestScreenSize|locale|fontScale|keyboard|keyboardHidden|navigation" android:label="@string/app_name" android:name="org.qtproject.qt5.android.bindings.MyActivity" android:screenOrientation="unspecified"&gt;
              &lt;intent-filter&gt;
                  &lt;action android:name="android.intent.action.MAIN"/&gt;
                  &lt;category android:name="android.intent.category.LAUNCHER"/&gt;
              &lt;/intent-filter&gt;
              &lt;meta-data android:value="AndroidTest" android:name="android.app.lib_name"/&gt;
              &lt;meta-data android:resource="@array/qt_sources" android:name="android.app.qt_sources_resource_id"/&gt;
              &lt;meta-data android:value="default" android:name="android.app.repository"/&gt;
              &lt;meta-data android:resource="@array/qt_libs" android:name="android.app.qt_libs_resource_id"/&gt;
              &lt;meta-data android:resource="@array/bundled_libs" android:name="android.app.bundled_libs_resource_id"/&gt;
              &lt;!-- Deploy Qt libs as part of package --&gt;
              &lt;meta-data android:value="1" android:name="android.app.bundle_local_qt_libs"/&gt;
              &lt;meta-data android:resource="@array/bundled_in_lib" android:name="android.app.bundled_in_lib_resource_id"/&gt;
              &lt;meta-data android:resource="@array/bundled_in_assets" android:name="android.app.bundled_in_assets_resource_id"/&gt;
              &lt;!-- Run with local libs --&gt;
              &lt;meta-data android:value="1" android:name="android.app.use_local_qt_libs"/&gt;
              &lt;meta-data android:value="/data/local/tmp/qt/" android:name="android.app.libs_prefix"/&gt;
              &lt;meta-data android:value="plugins/platforms/android/libqtforandroidGL.so:lib/libQt5QuickParticles.so" android:name="android.app.load_local_libs"/&gt;
              &lt;meta-data android:value="jar/QtAndroid.jar:jar/QtAndroidAccessibility.jar:jar/QtAndroid-bundled.jar:jar/QtAndroidAccessibility-bundled.jar" android:name="android.app.load_local_jars"/&gt;
              &lt;meta-data android:value="" android:name="android.app.static_init_classes"/&gt;
              &lt;!--  Messages maps --&gt;
              &lt;meta-data android:value="@string/ministro_not_found_msg" android:name="android.app.ministro_not_found_msg"/&gt;
              &lt;meta-data android:value="@string/ministro_needed_msg" android:name="android.app.ministro_needed_msg"/&gt;
              &lt;meta-data android:value="@string/fatal_error_msg" android:name="android.app.fatal_error_msg"/&gt;
              &lt;!--  Messages maps --&gt;
              &lt;!-- Splash screen --&gt;
              &lt;meta-data android:resource="@layout/splash" android:name="android.app.splash_screen"/&gt;
              &lt;!-- Splash screen --&gt;
          &lt;/activity&gt;
      &lt;/application&gt;
      &lt;uses-sdk android:minSdkVersion="14" android:targetSdkVersion="19"/&gt;
      &lt;supports-screens android:smallScreens="true" android:anyDensity="true" android:largeScreens="true" android:normalScreens="true"/&gt;
      &lt;uses-permission android:name="android.permission.BLUETOOTH"/&gt;
      &lt;uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/&gt;
      &lt;uses-permission android:name="android.permission.INTERNET"/&gt;
      &lt;uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/&gt;
  &lt;/manifest&gt;
  </code></pre>