When i try to write import org.junit.Test, just when I have completed writing import.jun it converts(auto-completes) it to import org.jun=acp#onPopupPost().
Is it some eclim autocomplete feature which is misbehaving or something else? I only face this issue when I am inside a project opened via eclim. Other wise there is no issue.
Looks like you have a problem with the AutoComplPop plugin; part of its mapping is inserted literally. I'm using the plugin myself, but haven't seen that issue. It may be interference with another plugin; have you done any updates to other plugins recently?! If you can reproduce the problem with a clean .vimrc and no other plugins loaded, submit an issue to the author.
To temporarily disable the plugin (without uninstalling), put the following into your ~/.vimrc:
let g:loaded_acp = 1