Please see the following test and error message. Jdk1.3 javac can compile T.java successfully.

% cat T.java
import W;
public class T {
}

% cat W.java
public interface W {
}

%/net/koori.sfbay/a/v01/jdk/1.4/beta/binaries/solsparc/bin/javac -verbose T.java
[parsing started T.java]
T.java:1: '.' expected
import W;
        ^
[parsing completed 464ms]
[checking T]
[loading /net/koori.sfbay/a/v01/jdk/1.4/beta/binaries/solsparc/jre/lib/rt.jar(java/lang/Object.class)]
[total 2268ms]
1 error