I guess that. Thanks. I feel a bit difficult in reading ThinkingInJAVA. Jabber, you're a good teacher and warm-hearted person. The beginners as me need your help. Don't care about the impolite words.
Jabber, when I read ThinkingInjava, I run a programme named AllOps.java. First, I compiled it successfully, afterwards, I run it, but error "Exception in thread 'main'...". Why?