"Unable to get system library for project" after I upgraded to Android SDK 2.3 and ADT 8.0

Question

Today I upgraded to Android SDK 2.3 and I also upgraded the Eclipse Plugin Androi Developer Tools 8.0 (from 0.9.9). I also upgraded my Java Development Kit to 1.6_22.

Now in Eclipse I get many errors in all my Android projects.

The error messages are like:

The type java.lang.Object cannot be resolved. It is indirectly referenced from required .class files.

How can I fix this so I can use my Android projects again?

In the Build Path for these projects, I don't have any references to an android.jar but a message:

Unable to get system library for project

Solution 1

That is rather difficult to answer, given the limited information you have supplied. Here are some suggestions:

• Make sure that an appropriate android.jar is in your build path, since that is where java.lang.Object would come from.

• Do a Project > Clean, to make sure you have 1.6 .class files, in case that is part of the problem.

• Try creating a new project from scratch and see if that works.

Solution 2

For me, the problem was that in the Project settings - Android tab, I had no Android version selected.

Solution 3

I had this problem even though I had a valid target selected. I fixed it by changing to a different target, applying changes and then changing back. That seems to have sorted it.

Solution 4

Project->Properties->Android : Select another Android Target (in my case Android 4.0.3) -> Apply changes. THEN select again your default Android Target, and that is all.

Hope this help.

Solution 5

This problem was caused for my old projects on a new machine that did not have an older Android SDK installed.

To fix, simply go into project.properties and observe your old version number:

# Project target.
target=Google Inc.:Google APIs:3

Simply update the version number, like so:

# Project target.
target=Google Inc.:Google APIs:7

You will find that Eclipse then picks up the right SDK version and starts working.

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Comments

[Jonas]

The android.jar seems to be in my Build path. I have already tried with Clean but it doesn't help. I get the same errors when I create new projects.

[Jonas]

If I look in the Properties for my project, under "Java Build Path" there is a message: Unable to get system library for project. I think this is the problem, but I don't know how to fix it.

[CommonsWare]

@Jonas: Go into Window > Preferences > Android and make sure your SDK is still configured with the appropriate directory.

[Jonas]

I was wrong, I just get this error on old projects and not on new projects and the old doesn't seem to have an android.jar in the build path, but a message Unable to get system library for project.

[CommonsWare]

@Jonas: You might get that if you have your project configured for some target that you no longer have on the system (e.g., you removed it as part of your round of upgrades). In the project properties dialog, go into the Android area and make sure you have a valid target checked.

[Jonas]

Thanks, that fixed most of the problems. No target were selected. But I use MapView from Google Maps in one project, and I don't have a target with Google Maps API.

[velazcod]

Update your ADT on eclipse, they just pushed a new version to deal with some bugs: twitter.com/#!/romainguy/status/12222143299330050

[Jonas]

I actually fixed this problem as CommonsWare described. And now I upgraded to ADT 8.0.1 and got the same problems again, but his fix solved it again.

[Thomas Ahle]

For me too, but with the addition that selecting a version in the Androids simply unset itself after reopening the preferences.

[Thiago Cardoso]

I had this same problem and I solved it with @CommonsWare comment (the 3rd one).

[Nilesh Gawade]

after that clean the project and then try to run it

[acedanger]

@CommonsWare's comment resolved it for me as well. Thank you!

[Robin Davies]

Worked for me. The project was referencing SDK 9 (which wasn't installed). When I edited the android version in the UI, the checkboxes wouldn't stay checked. Editing project.properties fixed things and allowed me to select the correct SDK version.

[Carl]

Yes, this actually re-created the entry for (in my case) Android 2.2 in my Java Build Path, which had been replaced by "unable to get system library for the project" after I installed a number of items. Now everything works as before.

[gonzobrains]

@CommonsWare You are a true Android Patriot! Suddenly all my errors disappeared in one fell swoop! Thanks!

[n611x007]

ticking in one of the boxes in <project> -> Properties -> Android -> Project Build Target did it. There was none selected. Strange. I've also copied android-support-v4.jar to a freshly-created <project's root>/libs folder - don't know if it has to do with anything because in itself it didn't help, but then the tick did.

[Andrew]

This is held under Project/Properties (not Settings) on my version of Eclipse. The solution (changing Android 4.3 Build Target from unchecked to checked) worked for me, but I don't understand how it became unchecked - the project worked fine earlier and seemed to stop working without any significant change.

[zungnv]

Thanks, it works. Somehow it lost the path to android.jar, just uncheck and check again , it will work

[n611x007]

what information should have been given, so it wouldn't be "limited" any more?

[n611x007]

I had a target selected, out of the three I'd installed, but selected a different one anyway, applied, then selected the original one and applied. then build. it fixed for me. just like Iker Martin's answer

[Kristy Welsh]

I also just closed and then reopened the project then everything worked.

[Neeraj Krishna]

Worked for me too on Android 6.0