1. Can we use assert as an identifier in java 1.4 .if we dont enable it . 2. In K &B chap 5 ,pg 378 it says ,with javac -source 1.4 abc.java ,asertions enabled . but i beleive it means ,telling Compiler to compile or code with 1.4 compiler ,in which assertions are Keywords. then how is this the way to enable assertions at compile time. and in java 1.5 ,assertions are always keyworkds.