WINDOWS 10
my libgdx version is 1.9.8
my eclipse version
Version: Oxygen.3a Release (4.7.3a)
Build id: 20180405-1200
1º Problem , after import the grandle project to eclipse oxigen my first error was
"The project was not built since its build path is incomplete. Cannot find the class file for android.os.Handler. Fix the build path then try building this project"
solution: chek all boxes on java build path https://imgur.com/a/0qwTA99
select API 20 https://imgur.com/a/eomDOeK
project > clean > clear project
2º problem - trying to run desktop java , erro Couldn't load file: badlogic.jpg
solution:
click with the 2 mouse button on the desktop folder assets Built Path > use as sorce folder desktop version now runing without problems.
3º Problem on tryng to run on android I get the error Unknown error: Unable to build: the file dx.jar was not loaded from the SDK folder!
solution:
on android projet folder on eclipse open project.properties and make it look like this
target=android-20
sdk.buildtools=23.0.1
I'm using android api 20 and sdk 23.0.1 because its what is on the libgdx site https://libgdx.badlogicgames.com/versions.html
4º error trying to run on android I get this java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.snarlmultimedia.summer/com.snarlmultimedia.summer.AndroidLauncher}: java.lang.ClassNotFoundException: Didn't find class "com.snarlmultimedia.summer.AndroidLauncher" on path: DexPathList[[zip file "/data/app/com.snarlmultimedia.summer-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.snarlmultimedia.summer-1, /vendor/lib, /system/lib]]
NO SOLUTION FOUNT YET.....
this was made with a clear instalation of libgdx using eclipse luna.. it's so frustratin...

note:I have some doubts about the version I installed, I just download the installer but the installer ask me to install API 27, i dont know if is 1.9.9-SNAPSHOT or 1.9.8, I whant it to run on old phones so i like to use api 20