See Assertion is like a Debugging Tool. it will help you to find the Bug at the runtime. for example you have program where you have some variable . you want to kno the valu of the variable at runtime . BEFORE ASSERTION what we do is going System.out.println and making console dirty,then we will find the value of the Variable. After Development we have to remove all the S.o.p in the program .OK after some days when we are going for maintaince mode we have to add s.o.p again. it is tedious prcess and you may find lot of Bug. SO sun came with new keyword in
SCJP 1.4 which will take care of debugging process. so u can on the assertion by using(-ea)option at the Runtime. when you dont want assertion you can leave it off ,because by default assertion id off. i am not going inside the syntax of assertion this is only 3000 feet high level overview. if you have any comments .WELCOME