I downloaded few source codes from Google source codes.
I executed them on Eclipse but R.java file is not created and therefore I got many errors saying that R cannot be resolved. There is no main.xml in layout too. Some other XML files are there. How can I execute these programs?
If your build.xml includes the "-resource-src" target (which it will if you include $SDK_DIR/tools/main_rules.xml or lib_rules.xml) you can rebuild it with ant.