CLASSES

Method Modifiers

8.4.3

8.4.2   Method Signature

The

signature

 of a method consists of the name of the method and the number and

types of formal parameters to the method. A class may not declare two methods

with the same signature, or a compile time error occurs. The example:

class Point implements Move {

int x, y;

abstract void move(int dx, int dy);

void move(int dx, int dy) { x += dx; y += dy; }

}

causes a compile time error because it declares two

move

 methods with the same

signature. This is an error even though one of the declarations is

abstract

.

8.4.3   Method Modifiers

MethodModifiers:

MethodModifier

MethodModifiers MethodModifier

MethodModifier: one of

public protected private

abstract static final synchronized native

The access modifiers

public

,

protected

, and

private

 are discussed in  6.6.

A compile time error occurs if the same modifier appears more than once in a

method declaration, or if a method declaration has more than one of the access

modifiers

public

,

protected

, and

private

. A compile time error occurs if a

method declaration that contains the keyword

abstract

 also contains any one of

the keywords

private

,

static

,

final

,

native

, or

synchronized

.

If two or more method modifiers appear in a method declaration, it is custom 

ary, though not required, that they appear in the order consistent with that shown

above in the production for

MethodModifier

.

8.4.3.1

abstract

Methods

An

abstract

 method declaration introduces the method as a member, providing

its signature (name and number and type of parameters), return type, and

throws

clause (if any), but does not provide an implementation. The declaration of an

abstract

 method

m

 must appear within an

abstract

 class (call it

A

); otherwise a

compile time error results. Every subclass of

A

that is not

abstract

 must provide

an implementation for

m

, or a compile time error occurs. More precisely, for every

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