Parent Control for small kids and big kids

class ParentControl {
  public void checkViewer(Person viewer, Program tv)
    throws ForbiddenViewerAndProgramException {
    if(viewer.getAge() < 13 && tv.isViolent()){
      throw new ViolentProgramException();
    }
    if(viewer.getAge() < 13 && tv.isSexual()){
      throw new ThisIsTooEarlyForYouException();
    }
    if(viewer.getAge() >= 30 && tv.isCartoon(){
      throw new GoOutAndFindDatesException();
    }
    viewer.watch(tv);
  }
}

The ClassCastException costs $40 (if refund is not accepted...)

class Me {
  public Data salvageDataFromBrokenPC(PC brokenPC){
    HDD hdd = brokenPC.getHDD();
    HDDEnclosure enclosure = buy(HDDEnclosure.class);
    enclosure.setHDD(hdd);
    return enclosure.getData();
  }
}

Exception in thread "main" java.lang.Exception: 
           Can't set IDE HDD to eSATA HDD Enclosure
...
Caused by: java.lang.ClassCastException: IDEHardDiskDrive
...
 at Me.salvageDataFromBrokenPC(Me.java:5)

Exception is not a good way to report problems...

class Manager {
  public Report report(){
    Developer member = callMember();
    try{
      member.report();
    }catch(NotEnoughTimeException e){
    }catch(NotEnoughResourceException e){
    }catch(NotEnoughMemoryOnPCException e){
    }catch(INeedYouToCompleteYourReviewException e)
    member.workHarder();
    return new Report("Everything is all right");
  }
}

Bad polymorphism - Me, my wife and my PC

interface WithOpenPC {
}

class ForWork implements WithOpenPC {
}

class ForHobby implements WithOpenPC {
}

class Me {
  public WithOpenPC whatAreYouDoingWithPC(){
    if(isIDEOpen() || isBrowserOpen()){
      return new ForHobby();
    }else{
      return new ForWork();
    }
  }
  ...
}

class MyWife {
  public void checkOn(Me husband){
      // This is supposed to cause compilation error! 
      // at least, ClassCastException!
      PlayingWithPC whateverItIs = 
        (PlayingWithPC)husband.whatAreYouDoingWithPC();
      complainTo(husband);
  }
  ...
}

Inheritance... it's a dream

public class Granpa {
  Property company = new Property();
  Property money = new Property();
}

class Dad extends Granpa {
  Property car = new Property();
  Property house = new Property();
}

class Me extends Dad {
  public Me(){
    consume();
  }
  private void consume(){
    super.company = null;
    super.money = null;
    super.car = null;
    super.house = null;
  }
}

Start blogging !!! ... but it may not last so long

public class Blogging extends Thread {

  public void run() {
    Blog today = new Blog();
    today.post();
  }

...

  private static Blogging singleton = new Blogging();

  protected Blogging(){}

  public static Blogging getInstance(){
    return singleton;
  }
}