About BabyJava, MicroJava, NanoJava [below referenced as xxxJava]:

xxxJava is a subset of Java.  The meaning of an xxxJava program
is given by its meaning as a Java program.

In an xxxJava class, each variable and method has a name which is different 
from all other names (of variables, methods, and formal parameters) which 
are declared in that class.  Notice that two methods of a class may have 
formal parameters with the same name.

The xxxJava statement 
  
   System.out.println( ... );

can only print integers.

The xxxJava expression 
   ... == ..."
can only compare integers.