It is considered preferable to initialize the fields of a superclass in its own constructor and
delegate to that constructor in a subclass. This will also allow declaring a field final
if it isn't changed after the construction.
Example:
class Super {
int x;
}
class Sub extends Super {
Sub(int _x) {
// Warning: x is declared in a superclass
x = _x;
}
}
To avoid the problem, declare a superclass constructor:
class Super {
final int x;
Super(int _x) {
x = _x;
}
}
class Sub extends Super {
Sub(int _x) {
super(_x);
}
}