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because the argument to f must be a variable integer, but i is a constant integer. This matching is a form of program correctness, and is known as const-correctness.This allows a form of programming by contract, where functions specify as part of their type signature whether they modify their arguments or not, and whether their return value is modifiable or not.
A global variable or static variable can be declared (or a symbol defined in assembly) with a keyword qualifier such as const, constant, or final, meaning that its value will be set at compile time and should not be changeable at runtime. Compilers generally put static constants in the text section of an object file along with the code itself ...
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.
Applying const to a pointer itself, as in SomeClass * const ptr, means that the contents being referenced can be modified, but the reference itself cannot (without casting). This usage results in behaviour which mimics the behaviour of a final variable reference in Java.
Used to declare an interface that only contains abstract or default methods, constant (static final) fields and static interfaces. It can later be implemented by classes that declare the interface with the implements keyword. As multiple inheritance is not allowed in Java, interfaces are used to circumvent it. An interface can be defined within ...
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 ...
public final class Constants {private Constants {// restrict instantiation} public static final double PI = 3.14159; public static final double PLANCK_CONSTANT = 6.62606896e-34;} Since Java 5 , one can use static import [ 4 ] to be able to use the constants without the Constants qualifier:
Of these, const is by far the best-known and most used, appearing in the standard library and encountered in any significant use of the C language, which must satisfy const-correctness. The other qualifiers are used for low-level programming, and while widely used there, are rarely used by typical programmers. [citation needed]