gistfile1.txt

A classic "switch on type" in Java. The draw method interrogates its parameter's class, and decides what to do as a resuilt.

interfact Thing { }

class Wall implemnts Thing { }

class Door implements Thing { }

class Chest implements Thing { }

void draw(Thing thing) {
    if(thing instanceof(Wall) drawWall(thing)
    else if(thing instanceof(Door) drawDoor(thing)
    else if(thing instanceOf(Chest) drawChest(thing)
    else drawBlank(thing)
    }
    
This is a switch on type, too. This time, it decided what to do not based on the particular sub-class of Thing, but on a type field inside Thing.

class Thing {
    public final int kind;
    }
    
void draw(Thing thing) {
    switch(thing.kind) {
        case WALL: drawWall(thing); break;
        case DOOR: drawDoor(thing); break;
        case CHEST: drawChest(thing); break;
        default: drawBlank(thing)
        }
    }