Android dex gives a BufferOverflowException when building

No need to downgrade the build tools back to 18.1.1¹, this issue is fixed with build tools 19.0.1.

If you can't use 19.0.1 for some reason then:

Make sure that the value of android:targetSdkVersion in AndroidManifest.xml matches target=android-<value> in project.properties. If these two values are not the same, building with build tools version 19.0.0 will end in the BufferOverflowException. ^Source

There is also some indication from comments on this post that you need to target at least 19 (android-19). Please leave a comment if this solution also works if your target is < 19.

This is how the fix looks for my project. The related AOSP issue is #61710.

^{1 If you really need to downgrade, you don't need to uninstall build tools 19.0.0, simply install 18.1.1 and add sdk.buildtools=18.1.1 to the local.properties file.}

Try what van said:

Right click your project → android tools → android support library.

Hope this helps :)