Builder pattern : Example

To build a house, we will take several steps : 

 1. build foundation 

 2. build frame 

 3. build exterior 

 4. build interior

Use an abstract class HouseBuilder to define these 4 steps.

Any subclass of HouseBuilder will follow these 4 steps to build house (that is to say to implement these 4 methods in the subclass)

// set steps for building a house

abstract class HouseBuilder {

    protected House house = new House();    

    protected String showProgress() {

        return house.toString();

    }

    abstract public void buildFoundation();

    abstract public void buildFrame();

    abstract public void buildExterior();

    abstract public void buildInterior();

}

class OneStoryHouse extends HouseBuilder {

    public OneStoryHouse(String features) {

        house.setType(this.getClass() + " " + features);

    }

    public void buildFoundation() {

        // doEngineering()

        // doExcavating()

        // doPlumbingHeatingElectricity()

        // doSewerWaterHookUp()

        // doFoundationInspection()

        house.setProgress("foundation is done");

    }

    public void buildFrame() {

        // doHeatingPlumbingRoof()

        // doElectricityRoute()

        // doDoorsWindows()

        // doFrameInspection()

        house.setProgress("frame is done");

    }

    public void buildExterior() {

        // doOverheadDoors()

        // doBrickWorks()

        // doSidingsoffitsGutters()

        // doDrivewayGarageFloor()

        // doDeckRail()

        // doLandScaping()

        house.setProgress("Exterior is done");

    }

    public void buildInterior() {

        // doAlarmPrewiring()

        // doBuiltinVacuum()

        // doInsulation()

        // doDryWall()

        // doPainting()

        // doLinoleum()

        // doCabinet()

        // doTileWork()

        // doLightFixtureBlinds()

        // doCleaning()

        // doInteriorInspection()

        house.setProgress("Interior is under going");

    }

}

class TwoStoryHouse extends HouseBuilder {

    public TwoStoryHouse(String features) {

        house.setType(this.getClass() + " " + features);

    }

    public void buildFoundation() {

        // doEngineering()

        // doExcavating()

        // doPlumbingHeatingElectricity()

        // doSewerWaterHookUp()

        // doFoundationInspection()

        house.setProgress("foundation is done");

    }

    public void buildFrame() {

        // doHeatingPlumbingRoof()

        // doElectricityRoute()

        // doDoorsWindows()

        // doFrameInspection()

        house.setProgress("frame is under construction");

    }

    public void buildExterior() {

        // doOverheadDoors()

        // doBrickWorks()

        // doSidingsoffitsGutters()

        // doDrivewayGarageFloor()

        // doDeckRail()

        // doLandScaping()

        house.setProgress("Exterior is waiting to start");

    }

    public void buildInterior() {

        // doAlarmPrewiring()

        // doBuiltinVacuum()

        // doInsulation()

        // doDryWall()

        // doPainting()

        // doLinoleum()

        // doCabinet()

        // doTileWork()

        // doLightFixtureBlinds()

        // doCleaning()

        // doInteriorInspection()

        house.setProgress("Interior is not started yet");

    }

}