Getting The Necessitas To Port To Android

So as I mentioned earlier I managed to port entimologist to Android. This post will hopefully explain how I did this.

The shopping list for this task is relatively straight forward:

  • Android SDK
  • Android NDK
  • Java development files (on openSUSE I use java-1_6_0-sun-devel)
  • ant (on openSUSE ant is too old, I use the binary tarball from the Apache site)
  • Qt Creator for Android SDK a.k.a Necessitas
  • Not necessary but could be helpful – Eclipse (on openSUSE don’t use the packages available as there are things missing that prevent building for android, use the binary tarball from the Eclipse site)
  • Ministro

First thing I had done was install and setup Eclipse, I then setup the Android SDK & Android NDK – that was done months ago. See the Android Developer site for good, clear instructions.

For setting up Necessitas, I used Alessandro’s post & video as a guide, but there are also details on Necessitas’ site.  After following the steps, I couldnt quite get things working, and I was starting to think that GNOME3 and Qt, were being children and bickering. No, they weren’t. It was me being a dufus! I hadn’t read the bit about ant needing to be >=1.8.0 :-) Download Ministro to somewhere safe (I popped mine in /opt/necessitas)

So to get things to work, I un-installed the ant rpm, extracted the bibnary tarball into ~/bin, and did a sudo ln -s ~/bin/apache-ant-1.8.2/bin/ant /usr/bin/ant

Now I wont pretend to know WTF I’m doing with Qt, as far as I’m concerned it’s another alien language. Problem is I needed to tell Necessitas what Qt libraries entomologist needed, I had no real idea. I had a look at the source and the spec file and got some clues, so I added the ones I thought were needed. I tried a build and got further than previously (now that I had the correct version of ant!). I was now getting some weird missing library error, but I couldn’t work it out. Along comes our new Boosters member Ismail Dönmez to the rescue.  There will be a lib$ that is created to work out which Qt libraries you need just do a readelf -d  lib$

In my case I did readelf -d and got:

~/workspace/Entomologist-build-android> readelf -d

Dynamic section at offset 0x4bda8 contains 29 entries:


  Tag        Type                         Name/Value

 0x00000001 (NEEDED)                     Shared library: []

 0x00000001 (NEEDED)                     Shared library: []

 0x00000001 (NEEDED)                     Shared library: []

 0x00000001 (NEEDED)                     Shared library: []

 0x00000001 (NEEDED)                     Shared library: []

 0x00000001 (NEEDED)                     Shared library: []

 0x00000001 (NEEDED)                     Shared library: []

 0x00000001 (NEEDED)                     Shared library: []

 0x00000001 (NEEDED)                     Shared library: []

 0x00000001 (NEEDED)                     Shared library: []

 0x0000000e (SONAME)                     Library soname: []

 0x00000010 (SYMBOLIC)                   0x0

 0x0000000f (RPATH)                      Library rpath: [/system/lib/data/data/eu.licentia.necessitas.ministro/files/qt/lib]

 0x00000019 (INIT_ARRAY)                 0x4c04c

 0x0000001b (INIT_ARRAYSZ)               8 (bytes)

 0x00000004 (HASH)                       0xd4

 0x00000005 (STRTAB)                     0x7d18

 0x00000006 (SYMTAB)                     0x2638

 0x0000000a (STRSZ)                      48318 (bytes)

 0x0000000b (SYMENT)                     16 (bytes)

 0x00000003 (PLTGOT)                     0x4ceb0

 0x00000002 (PLTRELSZ)                   5720 (bytes)

 0x00000014 (PLTREL)                     REL

 0x00000017 (JMPREL)                     0x154e8

 0x00000011 (REL)                        0x139d8

 0x00000012 (RELSZ)                      6928 (bytes)

 0x00000013 (RELENT)                     8 (bytes)

 0x6ffffffa (RELCOUNT)                   307

 0x00000000 (NULL)                       0x0


It may seem obvious, but look at the ones that have (NEEDED) in them ;-) I was missing Simply add the missing Qt library either by adding it manually in $PROJECT_LOCATION > Other files > android > res > values > libs.xml, or simply tick the required one in Qt Creator by going to the Projects button on the left > Run > Package Configurations > Libraries tab

When testing your app, make sure you select “Install Ministro system wide qt shared libraries installer” from the Projects button on the left > Run > Deploy configurations, then select the .apk in the “Choose apk” button.

Once that’s done, hit the “Play” button on the bottom left of Qt Creator and off you go :-)  I appreciate it may seem like a lot of work, but honestly it isn’t that much. I buggered around for ages cursing, mainly because I hadn’t checked my version of ant and didnt read the error message being spat out. I also didn’t know about readelf -d.  All I need to work out and try now is publishing to the Market So all in all have fun and keep being cute Qt :-D