Thread: Explicit Conversion?

the book that im reading says

"" + <number>

<< "this is the easy way to convert a numerical value to STRING"?

assuiming that the variable number is an integer.

is it what they called explicit conversion?

No, that's an implicit conversion (technically, it's not a cast at all in this case, see the reason below). An explicit conversion is one you specifically tell Java to do:

int a = 5;
String b = (String) a; // explicit

Note: because of the funny implementation of Strings in Java, this cast here will fail (the compiler will complain).

Reason: Java normally doesn't allow operator overloading. However, the + has been over-ridden for Strings to mean concatenation. The String concatenation method is able to take any primitive data type and convert it to a string equivalent value. However, because String is not a primitive data type, you cannot explicitly tell Java you want to cast an int to a String and vise versa.

concatenation doesn't really apply to primitives... It means "adding to the end of".

So:

"Hello" + " world"

is the same as

"Hello".concat(" world");