Is this legal?

[Debabrata Jana]

hi all,
Please answer this and give reasons.
Is this legal?
long longArr[];
int intArr[] = { 7 ,8 , 9};
longArr = intArr;

Thanks and regards
Debabrata

[JosAH]

hi all,
Please answer this and give reasons.
Is this legal?
long longArr[];
int intArr[] = { 7 ,8 , 9};
longArr = intArr;

Thanks and regards
Debabrata

Have you tried it? I guess you didn't (why not?) Of course it's not legal: an intArr
refers to a sequence of four byte ints that make up the array. A long is
supposed to refer to a sequence of eight byte longs that make up the array. Do
you want those conversions to take place behind your back? That'd be quite
dangerous ...

kind regards,

Jos

[r035198x]

hi all,
Please answer this and give reasons.
Is this legal?
long longArr[];
int intArr[] = { 7 ,8 , 9};
longArr = intArr;

Thanks and regards
Debabrata

The best way to learn this is to try it on the compiler and pay attention to the error messages that you get.

[dmjpro]

So Joash only Type Compatible Array Reference assignment is possible.
Right???

Kind regards,
Dmjpro.

[dmjpro]

hi all,
Please answer this and give reasons.
Is this legal?
long longArr[];
int intArr[] = { 7 ,8 , 9};
longArr = intArr;

Thanks and regards
Debabrata

I think u know how the Array is built in JAVA.
Actually they r implicitly a class.
And u don't get the class Name .. because this is managed by JVM.
So here u r assigning two incompatible object reference and it causes a disaster.
That's why u r getting a comipler error.
Right??
The expalination by Joash is very much effective but mine is the main reason behind it.
Have a good day.

Kind regards,
Dmjpro.

[JosAH]

So Joash only Type Compatible Array Reference assignment is possible.
Right???

There's a bit more to it; imagine the following little class hierarchy:

[code=java]
public class Transporter { ...}
public class Car extends Transporter { ... }
public class Submarine extends Transporter { ... }
[/code]

The two derived classes have an *is-a* relation with the base class: a Car *is-a*
Transporter and a Submarine *is-a* transporter.

But: an array of Car isn't an array of Transporter and an array of Submarine isn't
an array of Transporter. If there were, you would end up with this:

[code=java]
Transporter[] temp;
Car[] carpark= new Car[42];
carpark[0]= new Car(); // ok
temp= (Transporter[])carpark // error
temp[1]= new Submarine(); // of if the previous line were ok
[/code]

You may end up with a submarine in your carpark. ;-)

kind regards,

Jos

[dmjpro]

I didn't say that Joash.
U explained with class example.
Actually the array in java represented as Class implicitly.
So two incompatible Array object reference assignment is not possible.
M i right???

Kind regards,
Dmjpro.

[JosAH]

I didn't say that Joash.

I know; you said:

So Joash only Type Compatible Array Reference assignment is possible.

I explained that even if U is type compatible (assignable) from T that U[] and T[]
are not.

U explained with class example.
Actually the array in java represented as Class implicitly.
So two incompatible Array object reference assignment is not possible.
M i right???

Yep, that's correct.

kind regards,

Jos

[dmjpro]

Ok.
Thanks for ur suggestions.
Lot of thanks

Kind regards,
Dmjpro.