I'm learning name look up in Java, and coming from C++ I found interesting that even if Java lets me nest however many blocks of code,I am allowed to hide a name only in the first nested scope:
// name hiding-shadowing: local variables hide names in class scope
class C {
int a=11;
{
double a=0.2;
//{
// int a; // error: a is already declared in instance initializer
//}
}
void hide(short a) { // local variable a,hides instance variable
byte s;
for (int s=0;;); // error: s in block scope redeclares a
{
long a=100L; // error: a is already declared in (method) local scope
String s; //error: s is alredy defined in (method) local scope
}
}
}
this is weird from a C++ perspective,since there I can nest how many scopes I want,AND I'm able to hide variables as I like. Is this the normal behaviour of Java or am I missing something?
It's not about the "first nested scope" - it's a matter of Java allowing a local variable to hide a field, but not allowing it to hide another local variable. Presumably the designers of Java believed such hiding to be bad for readability.
Note that your example of a local variable in an instance initializer does not create an error - this code is valid:
class C {
int a = 11;
{
// Local variable hiding a field. No problem.
double a = 0.2;
}
}