0

Hello guys, How to Eliminate ifs and elses using polymorphism, so that the code is more compact and easy to understand.

```
public void update( ){
// is its dead it does nothing
if( dead ) return;
// see what movement it is doing
int dy = rising? -6: 6;
if( walking && rising )
move( (dir==LEFT? -6: 6), dy);
else if( walking )
move( (dir==LEFT? -4: 4), dy);
else
move( 0, dy );
if( shooting )
fire();
// see the bouding rectangle to check for colisions
Rectangle ra = getBounds();
// if it is not draggin, see if it touches any draggable
if( !isDragging() ){
for( WorldElement t : getWorld().getDraggables() ){
Rectangle rt = t.getBounds();
if( rt.intersects( ra ) ){
/* ALL THESE IFS MUST BE REMOVED */
/* ALL THESE IFS MUST BE REMOVED */
/* ALL THESE IFS MUST BE REMOVED */
if( t instanceof Fuel ) {
Fuel f = (Fuel)t;
draggedFuel = f;
f.pickUp();
}
else if( t instanceof Treasure ){
Treasure tre = (Treasure) t;
draggedTreasure = tre;
tre.pickUp();
}
else if( t instanceof Spaceship ){
Spaceship s = (Spaceship)t;
draggedShip = s;
s.pickUp();
}
int dtx = (ra.x - rt.x) + (ra.width - rt.width)/2;
int dty = (ra.y - rt.y) + (ra.height - rt.height);
t.move(dtx, dty );
break;
}
}
}
// if it is dragging then check if its over the drop area
if( isDragging() ){
Rectangle drop = getWorld().getMainSpaceship().getDropArea();
/* ALL THESE IFS MUST BE REMOVED */
/* ALL THESE IFS MUST BE REMOVED */
/* ALL THESE IFS MUST BE REMOVED */
if( draggedFuel != null ){
Rectangle rt = draggedFuel.getBounds();
if( drop.intersects( rt ) ){
draggedFuel.release();
int dtx = (drop.x - rt.x) + (drop.width - rt.width)/2;
draggedFuel.move(dtx, 0 );
draggedFuel = null;
}
}
if( draggedTreasure != null ){
Rectangle rt = draggedTreasure.getBounds();
if( drop.intersects( rt ) ){
draggedTreasure.release();
int dtx = (drop.x - rt.x) + (drop.width - rt.width)/2;
draggedTreasure.move(dtx, 0 );
draggedTreasure = null;
}
}
if( draggedShip != null ){
Rectangle rt = draggedShip.getBounds();
if( drop.intersects( rt ) ){
draggedShip.release();
int dtx = (drop.x - rt.x) + (drop.width - rt.width)/2;
draggedShip.move(dtx, 0 );
draggedShip = null;
}
}
}
// if the ship is full then test if it hits the ship to win the level
if( getWorld().getFuelPercentage() == 100 ){
Spaceship n = getWorld().getMainSpaceship();
if( n.getBounds().intersects( getBounds() ) ){
getWorld().completed();
setPosition( new Point(-100,-100) );
}
}
setJetPacOn( true );
}
/*** move the astronaut
* @param. The x distance to move
* @param. The y distance to move
*/
public void move(int dx, int dy ) {
if( getImage().getPosicao().y + dy < 0 )
dy = -getImage().getPosicao().y;
if( getImage().getPosicao().x < 0 )
dx += getWorld().getWidth();
else if( getImage().getPosicao().x > getWorld().getWidth() )
dx -= getWorld().getWidth();
super.move( dx, dy );
// also move the dragged
if( isDragging() ){
/*
/* ALL THESE IFS MUST BE REMOVED */
/* ALL THESE IFS MUST BE REMOVED */
/* ALL THESE IFS MUST BE REMOVED */
if( draggedFuel != null )
draggedFuel.move( dx, dy );
else if( draggedTreasure != null )
draggedTreasure.move( dx, dy );
else if( draggedShip != null )
draggedShip.move( dx, dy );
}
}
//}
/**
* drops what it is dragging
*/
public void drop(){
if( !isDragging() )
return;
/* ALL THESE IFS MUST BE REMOVED */
/* ALL THESE IFS MUST BE REMOVED */
/* ALL THESE IFS MUST BE REMOVED */
if( draggedFuel != null ){
draggedFuel.release();
draggedFuel = null;
}
else if( draggedTreasure != null ){
draggedTreasure.release();
draggedTreasure = null;
}
else if( draggedShip != null ){
draggedShip.release();
draggedShip = null;
}
}
```