subhashis - Developer IT

HashMap null key

- by subhashis

HashMap allows one null key and any number of null values. what is the use of it?

Java ArrayList Middle

- by subhashis

How to find the middle of an ArrayList ?

what should be the return type of the hashCode()

The signature of the hashCode() method is public int hashCode(){ return x; } in this case x must be an int(primitive) but plz can anyone explain it to me that the number which the hashCode() returns must be a prime number, even number...etc or there is no specification ? the reason behind i am asking this question is i have seen it in different ids the auto generated code always returns a prime number, so i need to know why? thanks in advance

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is hashCode() must return a prime number

- by subhashis

The signature of the hashCode() method is public int hashCode(){ return x; } in this case x must be an int(primitive) but plz can anyone explain it to me that the number which the hashCode() returns must be a prime number, even number...etc or there is no specification ? the reason behind i am asking this question is i have seen it in different ids the auto generated code always returns a prime number, so i need to know why? thanks in advance

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oracle primary_key and foreign_key

- by subhashis

Is it possible to maintain relationship between two tables without primary key and foreign key if it is possible then how?

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Interview question: about Java serialization and singletons

- by subhashis

In an interview the interviewer asked me the following question: is it possible to serialize a singleton object? I said yes, but in which scenario should we serialize a singleton? And is it possible to design a class whose object can not be serialized?

Developer IT