Question

Sorry to ask such a noob question, but the NDK documentation is wrong (r7b):

If you are developing in Eclipse with ADT, use the New Project Wizard
to create a new Android project for each sample, using the “Import
from Existing Source” option and importing the source from
<ndk>/apps/<app_name>/project/. Then, set up an AVD, if necessary, and
build/run the application in the emulator.

There is no “apps” folder, and the samples do not contain a “project” folder. So … what is the correct way to run a sample?

Also, can I configure Eclipse to build the C++ portion of the code automatically?

Answer 1

1. Click File | New | Project…
2. Choose Android project, Next
3. Project Name: This is the project name shown in Package Explorer. It is just a string stored in the .project file that Eclipse creates. No file or folder is created with this name, and the output binaries do not seem to contain this name.
4. Click "Create project from existing source"
5. Location: choose the project’s root folder, e.g. …/android-ndk-r7b/samples/bitmap-plasma
6. Click Next and choose your target API. Eclipse does not seem to allow this to be changed later, at least not from the GUI. I don’t know why Eclipse does not simply get this information from <uses-sdk> in AndroidManifest.xml or from the "target" line in default.properties. I also don’t know why the two may be different (e.g. in the bitmap-plasma sample, target=android-9 but <uses-sdk android:minSdkVersion="8"/>.)
7. Click next and consider changing the "Package Name" field which defaults to "your.package.namespace". However, the project will run fine if you do not change this field. Leave "Create Activity" and "Create a Test Project" unchecked.
8. Click Finish. Eclipse will create numerous extra files (e.g. .classpath, .project, project.properties) and folders (bin, gen, assets) alongside the existing code. That’s in addition to the output folders created by ndk-build (obj and libs).

Eclipse won’t build the native code by itself, but it will automatically deploy the native code (e.g. libplasma.so) if it is aware of it. After you build the native code on the command line, e.g.:

C:\...\android-ndk-r7b\samples\bitmap-plasma>..\..\ndk-build
Gdbserver      : [arm-linux-androideabi-4.4.3] libs/armeabi/gdbserver
Gdbsetup       : libs/armeabi/gdb.setup
Gdbserver      : [arm-linux-androideabi-4.4.3] libs/armeabi-v7a/gdbserver
Gdbsetup       : libs/armeabi-v7a/gdb.setup
"Compile thumb : plasma <= plasma.c
SharedLibrary  : libplasma.so
Install        : libplasma.so => libs/armeabi/libplasma.so
"Compile thumb : plasma <= plasma.c
SharedLibrary  : libplasma.so
Install        : libplasma.so => libs/armeabi-v7a/libplasma.so

Right-click your project and choose "Refresh", otherwise Eclipse might fail to upload the native code when it starts the emulator.

Finally, to run the sample, right-click the project and choose Run As | Android application. See here about choosing which emulator is used.

See here about configuring Eclipse to build the native code automatically.

I am curious why NDK produces two *.so files with very different sizes for each ABI, e.g. it creates libs/armeabi-v7a/libplasma.so (15 KB) but also obj/local/armeabi-v7a/libplasma.so (63 KB). Anyone know the difference?