template method pattern

Question

May i know how to create childClass if my childClass method getInfoFromDB() and saveToDB() need to do different logic?

public abstract class BaseClass {
    public abstract Object doTransaction();
    public Object executeTrans() {
          //do something
          tx.begin();            
          this.doTransaction();
          tx.commit();

    }
}
public childClass extends BaseClass{
    @Override
    public Object doTransaction(){
        //overide to get something from database so can only be used for getInfoFromDB() and not for saveToDB()
        return something;
    }
    public List<String> getInfoFromDB(){
        super.executeTrans();
    }
    public void saveToDB(){
        super.executeTrans() ;
    }
}

Answer 1

You should use the template pattern in this case, something like this:

public abstract class BaseClass 
{      
  public Object executeTrans(Template template) 
  {
    tx.begin();            
    template.doTransaction();
    tx.commit();    
  }
}

public interface Template
{
  public void doTransaction();
}

public childClass extends BaseClass
{
  public List<String> getInfoFromDB()
  {
    executeTrans(
      new Template()
      {
        public void doTransaction() 
        {
          ...do get info from DB here.
        }
      }
    );
  }

  public void saveToDB()
  {
    executeTrans(
      new Template()
      {
        public void doTransaction() 
        {
          ...do save to DB here.
        }
      }
    );
  }
}

Saying that, I'd advise using the Spring JDBC template classes rather than rolling your own - they've been tried and tested and have solved the problems you'll run into with nested transactions etc.