Antarmuka luwih saka antarmuka. Iku prilaku.

"Halo, Amigo! Iki aku-maneh. Aku pengin menehi sudut pandang liyane babagan antarmuka. Sampeyan ndeleng, biasane kelas minangka model obyek tartamtu. Ing kontras, antarmuka luwih kaya kemampuan obyek utawa peran, tinimbang obyek kasebut dhewe."

Contone, barang kayata mobil, sepedha, sepedha motor, lan roda paling apik dituduhake minangka kelas lan obyek. Nanging kabisan, kaya «Aku bisa mindhah», «Aku bisa nindakake wong», lan «Aku bisa parkir», luwih apik dituduhake minangka antarmuka. Priksa conto iki:

interface Moveable
{
void move(String newAddress);
}

interface Driveable
{
void drive(Driver driver);
}

interface Transport
{
void addStuff(Object stuff);
Object removeStuff();
}

class Wheel implements Moveable
{
...
}

class Car implements Moveable, Drivable, Transport
{
...
}

class Skateboard implements Moveable, Driveable
{
...
}

Antarmuka banget nyederhanakake urip programer. Program asring duwe ewu obyek, atusan kelas, lan mung sawetara lusin antarmuka (peran). Ana sawetara peran, nanging bisa digabungake kanthi pirang-pirang cara (kelas).

Intine yaiku sampeyan ora kudu nulis kode sing nemtokake interaksi karo saben kelas liyane. Sampeyan mung kudu sesambungan karo peran (antarmuka).

Mangkene carane katon ing kode:

static interface WallBuilder
{
void buildWall();
}

static class WorkerRobot implements WallBuilder
{
void buildWall()
 {
…
 }
}
static class GuardRobot implements WallBuilder
{
void buildWall()
 {
…
 }
}
static class WateringCan
{
…
}

public static void main(String[] args)
{
 //add all robots to a list
 ArrayList robots = new ArrayList();
 robots.add(new WorkerRobot());
 robots.add(new GuardRobot());
 robots.add(new WateringCan());

 //build a wall if you can
 for (Object robot: robots)
 {
  if (robot instanceof WallBuilder)
  {
   WallBuilder builder = (WallBuilder) robot;
   builder.buildWall();
   }
  }
 }
}

"Sing apik tenan menarik. Aku tau ngimpi sing antarmuka bisa dadi topik menarik."

"Lan sawetara! Bebarengan karo polymorphism, iku babar blas pikiran-ndamu."