saikatbarman,
It looks like you may have your java level at 1.4. Map has never had a put(int, obj) method but Java 1.5 introduced autoboxing, where primitives, such as int, would be automatically wrapped in the appropriate object (Integer, in this case), if needed.
You can set the java compliance level to default to 1.5 (or 1.6) using Window->Preferences->Java->Compiler, or you can set it on a per project basis by right clicking on the project and selecting Properties->Java Compiler.
Let us know if this works for you.