book example

[dolly shah]

chapter:7, example 7,page no;626
Can anybody help me to solve this example? I am not getting it,
Thanks in advance.

[dolly shah]

I want to add that , I am not getting second method. Why we dont need instanceof test for boolean equals().

[fred rosenberger]

Dolly,

You don't mention WHAT book. Even at that, not everyone HAS whatever book you are talking about. Can you post the actual code/question?

[Padma Asrani]

Hi

I guess you are talking about K&B test.

The instanceof test is required for equals method to know that you are comparing the objects which are comparable.

This statement might be vague, so I will give an example.
For example If I have a code like this.

    
String s1 ="a";
StringBuffer s2 = "a";
 
if(s1.euqals(s2))
   System.out.println("Equal");
else
  System.out.println("Not Equal");

This returns Not Equal because the String and StringBuffer are not comparable. Both classes derived from Object but there is not relation between String class Objects and StringBuffer class Objects, so the instanceof test inside equals method in String class will fail and as a result it will return false.

I hope this is clear.

Regards
Padma

[dolly shah]

Fred I am talking about K & B book.

Padma I got your point. Thanks for that.
But here in boolean equals() we have to do instanceof test for ToDos. So my question was that?