//test1.java:13: warning: as of release 1.4, assert is a keyword, and may not be u
sed as an identifier
You not specified that the class is 1.4 so the compiler is supposing its 1.3 or older code. So, you can use assert as an identifier but is not advised to.
//test1.java:13: ';' expected
//assert x < 3;
test1.java:13: cannot resolve symbol
symbol : class assert
location: class test1
assert x < 3;
^
test1.java:13: x is already defined in asserta()
assert x < 3;
The code is 1.3 so assert is a normal
word that can be used as a identifier. By this angle this line is wrong.