8.4.3

Method Modifiers

CLASSES

A method that is not declared

static

 is called an

instance method,

 and some 

times called a non 

static

 method). An instance method is always invoked with

respect to an object, which becomes the current object to which the keywords

this

 and

super

 refer during execution of the method body.

8.4.3.3

final

Methods

A method can be declared

final

 to prevent subclasses from overriding or hiding

it. It is a compile time error to attempt to override or hide a

final

 method.

A

private

 method and all methods declared in a

final

 class ( 8.1.2.2) are

implicitly

final

, because it is impossible to override them. It is permitted but not

required for the declarations of such methods to redundantly include the

final

keyword.

It is a compile time error for a

final

 method to be declared

abstract

.

At run time, a machine code generator or optimizer can easily and safely

 inline  the body of a

final

 method, replacing an invocation of the method with

the code in its body, as in the example:

final class Point {

int x, y;

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

}

class Test {

public static void main(String[] args) {

Point[] p = new Point[100];

for (int i = 0; i < p.length; i++) {

p[i] = new Point();

p[i].move(i, p.length 1 i);

}

}

}

Here, inlining the method

move

 of class

Point

 in method

main

 would transform

the

for

 loop to the form:

for (int i = 0; i < p.length; i++) {

p[i] = new Point();

Point pi = p[i];

pi.x += i;

pi.y += p.length 1 i;

}

The loop might then be subject to further optimizations.

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