I download from Internet same java code for study input method.
Now if I compile it with Jcreator as a project it's work (partially)

If I compile separate source directly by javac, the compile mark some errors.
as two program that point each other that settle 2 classes.
for example program A define a class A1 and set a variable at class B1, but class B1 is in the program B that set a variable at class A1.

How ide(Jcreator) can compile the two source correctly ?