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c+=i != c=c+i

 
Greenhorn
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Hi,

I've been lurking for some time now. My SCJP 5.0 exam is in two weeks so I'm currently learning quite extensively.

On examulator (http://www.examulator.com/phezam/question.php) today's question was:



Correct answer is 2.

My question is: why doesn't this compile?



.. if this does?


In both cases you add an int to the char. There's obviously some catch with the operators.

Can someone please explain this?
 
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Lidija when you use the += (or any other compound assignment operator like *= or -=), implicit type cast happens. So you can do these

char += int

byte += int
 
Ranch Hand
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This works though: c = (char)(c + i);

 
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s+=i;// compiles

But why dosent i+=s;???
 
Lidija Sketa
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Thanks Ankit and Brian, that makes sense.

s += i
compiles because you can append int to String.

But you can't "append" String to int.
 
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To Abhi Vijay

s+=i will comile because if we add anything to string it will result in string and string can hold the result but integer cannot( in i+=s).

Thanks,
Geeta Vemula
 
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For reference, see JLS - 15.26.2.
 
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