I reinstalled my eclipse. and then imported all the projects in the Eclipse, but every project has a common error:
Cannot find the class file for java.lang.Object. at Line 1.
I have checked my Java Path. But not able to sort it out.
I reinstalled my eclipse. and then imported all the projects in the Eclipse, but every project has a common error:
Cannot find the class file for java.lang.Object. at Line 1.
I have checked my Java Path. But not able to sort it out.
Right click on Project--> Properties, Java Build Path.

Check whether you have JRE installed. If installed click on EDIT and check whether its pointing to correct location

Check this if it works:
There is a problem with your java repositories. I guess..:
goto Help>Install New Software> Click on Add Button .
on popup:
Name: ADT
Location:https://dl-ssl.google.com/android/eclipse
Install all the available softwares in the list. This may work.
Have a good day!!!
Class file java.lang.ObjectA quicker way will be
Right Click Project---> Properties--->Build Path--->Add External Jars--> Find your android-xx.Jar e.g android-17.jar
In my case I'm using the adt and it is here
E:\adt-bundle-windows-x86_64-20130219\adt-bundle-windows-x86_64-20130219\sdk\platforms\android-17
Hope it helps
This happened to me when I tried to merge two branches of an Android project using eGit. For some reason my build path basically disappeared (possibly one of the files was untracked).
To get the JRE and android libraries back, I just right-clicked on the project in the project explorer, and hit Android Tools -> Fix Project Properties (these options are only available if you have Android ADT installed).
I just had this problem and all I had to do was clean the entire workspace, i.e. all projects in the workspace. The error went away.
I've had this problem after installing a newer version of Google ADT. The solution, at least running OS X, is to make a copy of your project to a safe location, delete it completely from Eclipse and then import it again using File->Import->General->Existing Projects into Workspace.
FYI
I am Using Google's on OS X Mavericks Android Developer Tools Build: v22.2.1-833290
but I am almost sure I have done in the past with previous OSX and ADT versions.