Type casting error in Java

I am learning java (or should I say, filling in the holes) from a reputable learning source (say no more) it said, if fact I am going to feed it back to source I made my purchase from, they said

Code :

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int myInt;
long myLong = 123987654321L;
myInt = (int) (myLong);

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saying that the number might be chopped

I thought why not give it a go, to find myInt comes out to be -566397263
Well one thing I learnt, never trust down type casting.

Quote:

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Originally Posted by Eric

Well one thing I learnt, never trust down type casting.

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Downcasting should only be done where it can be trusted - generally only at system boundaries where objects are being generated and introduced to the system.

But casting a long to an int is not downcasting, it is a 'casting conversion' (specifically a narrowing primitive conversion). Downcasting is when you cast a superclass type to a subclass type.

A narrowing primitive conversion is converting a larger primitive numeric type to a smaller one. For full details, see Narrowing Primitive Conversions.

Now I am not sure why I posted this thread?

I suppose the best idea might be to test to see if that Long variable could fit down into a Int, and if it is outside the range of -2147483648 to 2147483647 print off something like "done but with error!"

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