From http://forum.java.sun.com/thread.jsp?forum=316&thread=527393&tstart=0&trange=50

Compile the following code with 1.4.2_04:

import java.io.File;

public class Over15A extends File {
public Over15A(String s) { super(s); }
public int compareTo(File file) { return 0; }
public int compareTo(Object o) { return 0; }
}



and try to compile the following code with 1.5-beta2:


public class Over15B extends Over15A {
public Over15B(String s) { super(s); }
}



Error is:

Over15B.java:1: name clash: compareTo(java.lang.Object) in Over15A and compareTo(T)
in java.lang.Comparable<java.io.File> have the same erasure, yet neither overrides the other

File class is a key, because in 1.5 it is defined like this: "File implements Comparable<File>"