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The blank final, which was introduced in Java 1.1, is a final variable whose declaration lacks an initializer. [9] [10] Previous to Java 1.1, a final variable was required to have an initializer. A blank final, by definition of "final", can only be assigned once. i.e. it must be unassigned when an assignment occurs.
In C#, only C# built-in types can be declared as const; user-defined types, including classes, structs, and arrays, cannot be const. [22] Java does not have const – it instead has final, which can be applied to local "variable" declarations and applies to the identifier, not the type. It has a different object-oriented use for object members ...
Java has a qualifier called final that prevents changing a reference and makes sure it will never point to a different object. This does not prevent changes to the referred object itself. Java's final is basically equivalent to a const pointer in C++. It does not provide the other features of const.
However, Java initially left open the possibility of implementing const, noticeable in that const is a reserved word, though it is not actually used as a keyword. Instead, Java has the object-oriented keyword final , which is used to qualify attributes (and thence also for local variables) as constant, but not to qualify types.
Although reserved as a keyword in Java, const is not used and has no function. [2] [26] For defining constants in Java, see the final keyword. goto Although reserved as a keyword in Java, goto is not used and has no function. [2] [26] strictfp (added in J2SE 1.2) [4] Although reserved as a keyword in Java, strictfp is obsolete, and no longer ...
In the Dart language, used in the Flutter SDK, the conventions are similar to those of Java, except that constants are written in lowerCamelCase. Dart imposes the syntactic rule that non-local identifiers beginning with an underscore ( _ ) are treated as private (since the language does not have explicit keywords for public or private access).
Unless a developer checks any implemented interfaces when adding a constant to a class, or does so but makes a typo in the name of the added constant, the value of a constant can be silently changed. Consider Example 2 below. Note that the Java libraries use constant interface pattern themselves.
Const-ness is propagated as a means to enforce, at compile-time, correctness of the code with respect to mutability of objects (see const-correctness). final provides a version of const, [9] equivalent to type* const pointers for objects and const for primitive types. Immutability of object members achieved via read-only interfaces and object ...