this.troops.add( unit );
this.troops.addElement( unit );
    public void load( Entity unit ) throws IllegalArgumentException {        // If we can't load the unit, throw an exception.        if ( !this.canLoad(unit) ) {            throw new IllegalArgumentException( "Can not load " +						unit.getShortName() +						" into this troop space." );        }        // Decrement the available space.        // POSSIBLE BUG: we may have to take the Math.ceil() of the weight.        this.currentSpace -= unit.getWeight();        // Add the unit to our list of troops.        this.troops.add( unit );    }