When some datas are inserted in to a DB table from a jsp page, how do i get the primary key in my table autogenerated?? finiding out the highest value for the primary key in the table? Pls help me wid the coding in JAVA or HTML.. I use SQL*PLus.

you need to create a sequence. As you can guess this is an object that gives you numbers from sequence. then you should get next value from sequence. so you will always have different pk. here is a link that shows you how to create and use it.
after creating it you will probably do something like that

insert into a(pk,col1,col2) values (sqn.nextval,'value1','value3')

you can use either a sequence or the max value of PK field +1 for the next unique not null value.