8.4.8

Examples of Method Declarations

CLASSES

8.4.8.1

Example: Overriding

In the example:

class Point {

int x = 0, y = 0;

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

}

class SlowPoint extends Point {

int xLimit, yLimit;

void move(int dx, int dy) {

super.move(limit(dx, xLimit), limit(dy, yLimit));

}

static int limit(int d, int limit) {

return d > limit ? limit : d <  limit ?  limit : d;

}

}

the class

SlowPoint

 overrides the declarations of method

move

 of class

Point

with its own

move

 method, which limits the distance that the point can move on

each invocation of the method. When the

move

 method is invoked for an instance

of class

SlowPoint

, the overriding definition in class

SlowPoint

 will always be

called, even if the reference to the

SlowPoint

 object is taken from a variable

whose type is

Point

.

8.4.8.2

Example: Overloading, Overriding, and Hiding

In the example:

class Point {

int x = 0, y = 0;

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

int color;

}

class RealPoint extends Point {

float x = 0.0f, y = 0.0f;

void move(int dx, int dy) { move((float)dx, (float)dy); }

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

}

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