i'll try to answer because i can't understand what you mean absolutely.
before i answer, i ask to you , what kind of java  editor you use ?
if you use notepad, it's impossible to do that.
but if you use java editor like JCreator, while we compile the program,
if there any mistake, jcreator will display  error message. if we still
force to execute the program, may be we will see the message  box about the
program's error.
that's all from me. may ny one else can explain about this ???