Name: mgC56079 Date: 09/15/97



java.text.RuleBasedCollator.equals(null) throws NullPointerException.
Should return false.

--- Here is the general contract of equals() (see JLS, 20.1.3) ----
20.1.3 public boolean equals(Object obj)

This method indicates whether some other object is "equal to" this one.

The general contract of equals is that it implements an equivalence relation:

      It is reflexive: for any reference value x, x.equals(x) should return true.
      It is symmetric: for any reference values x and y, x.equals(y) should return
      true if and only if y.equals(x) returns true.
      It is transitive: for any reference values x, y, and z, if x.equals(y) returns
      true and y.equals(z) returns true, then x.equals(z) should return true.
      It is consistent: for any reference values x and y, multiple invocations of
      x.equals(y) consistently return true or consistently return false, provided
      no information used by x and y in equals comparisons is modified.
      For any non-null reference value x, x.equals(null) should return false.
                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
---------Here is the test demonstrating the bug (RBC.java) --------------
import java.text.*;

public class RBC {

public static void main(String args[]) {

  try {
    RuleBasedCollator rbc=new RuleBasedCollator("< a < b");
    System.out.println(rbc.equals(null));
  }
  catch (ParseException e) {
    System.out.println(e);
  }

}

}
---------Output from the test---------------------
% java RBC
java.lang.NullPointerException
at java.text.Collator.equals(Collator.java:407)
at java.text.RuleBasedCollator.equals(RuleBasedCollator.java:485)
at RBC.main(RBC.java:9)
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