question on equals() method

[velan vel]

hai ranchers
here how is ans b & c
can any one explain

Given that b and c refer to instances of wrapper classes, which two statements are
true? (Choose two)
A. b.equals(b) returns true.
B. b.equals(c) returns the same result as b == c.
C. b.eqials(c) can return false even if c.equals(b) returns true.
D. b.equals(c) throws an exception if b and c are different wrapper types.
E. b.equals(c) returns false if the type of wrapper objects being compared are
different.
Answer: B, C

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$ Velan Vel @ SCJP 1.4 $
You learn From Your Failures, Others Will Learn From Your Success
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[Srinivasa Raghavan]

A. b.equals(b) returns true.
B. b.equals(c) returns the same result as b == c.
C. b.eqials(c) can return false even if c.equals(b) returns true.
D. b.equals(c) throws an exception if b and c are different wrapper types.
E. b.equals(c) returns false if the type of wrapper objects being compared aredifferent.

I feel A & E are true.
[ December 07, 2005: Message edited by: Srinivasa Raghavan ]

[Tilo Hemp]

B is wrong, as b == c compares object references, also in the case of wrappers.

A is correct. It is interesting that the following fragment

Double d = Double.NaN;
Double e = Double.NaN;
System.out.println(d.equals(e));
System.out.println(d.equals(d));
System.out.println(d ==d);
System.out.println(Double.NaN == Double.NaN);
System.out.println(Double.NaN == e);

produces the output
true
true
true
false
false

[harish shankarnarayan]

A & E are true
how come u say b and c .
just try it out it wont

[xie li]

why C is wrong?

[rey anz]

A & E are correct, as for C it is incorrect because equals method is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.

[Sasikanth Malladi]

Yes, I think A & E are correct, assuming that b and c are instances of two different wrapper classes.
Velan, what is the source where you got this question from?
Sashi
[ December 09, 2005: Message edited by: Sasikanth Malladi ]