EXPRESSIONS

Compile Time Step 2: Determine Method Signature

15.11.2

15.11.2   Compile Time Step 2: Determine Method Signature

The hand writing experts were called upon for their opinion of the signature . . .

 Agatha Christie,

The Mysterious Affair at Styles

 (1920), Chapter 11

The second step searches the class or interface determined in the previous step for

method declarations. This step uses the name of the method and the types of the

argument expressions to locate method declarations that are both

applicable

 and

accessible

, that is, declarations that can be correctly invoked on the given argu 

ments. There may be more than one such method declaration, in which case the

most specific

 one is chosen. The descriptor (signature plus return type) of the most

specific method declaration is one used at run time to do the method dispatch.

15.11.2.1

Find Methods that are Applicable and Accessible

A method declaration is

applicable

 to a method invocation if and only if both of

the following are true:

The number of parameters in the method declaration equals the number of

argument expressions in the method invocation.

The type of each actual argument can be converted by method invocation con 

version ( 5.3) to the type of the corresponding parameter. Method invocation

conversion is the same as assignment conversion ( 5.2), except that constants

of type

int

 are never implicitly narrowed to

byte

,

short

, or

char

.

The class or interface determined by the process described in  15.11.1 is

searched for all method declarations applicable to this method invocation; method

definitions inherited from superclasses and superinterfaces are included in this

search.

Whether a method declaration is

accessible

 to a method invocation depends

on the access modifier (

public

, none,

protected

, or

private

) in the method

declaration and on where the method invocation appears.

If the class or interface has no method declaration that is both applicable and

accessible, then a compile time error occurs.

In the example program:

public class Doubler {

static int two() { return two(1); }

private static int two(int i) { return 2*i; }

}

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