良好实践/设计模式是否可以解决嵌套问题？

Question

Currently I have a code like this:

for (each item) {
   if (item == 'x') { 
      print
   }
   if (item == 'y) {
      print
   } 
}

Now, I there is an additional requirement - I want the same checks but instead of printing, I need to insert in DB.

ie

for (each item) {
   if (item == 'x') { 
      insertDB
   }
   if (item == 'y) {
      insertDB
   } 
}

This has duplicated code, so flags come to my thought.

for (each item) {
   if (item == 'x') { 
      if (insertDB) {
          insertDB
      } else {
          print
      }
   }
   if (item == 'y) {
      if (insertDB) {
         insertDB
      } else {
         print
      }
   } 
}

This has clearly caused a lot of if-else clutter. My Object oriented programming tells me a new idea.

for (each item) {
   if (item == 'x') { 
      obj.doItemXAction();
   }
   if (item == 'y) {
      obj.doItemXAction();
   } 
}

Object obj = new PrintObj();
Object obj = new DBInsertObj();

Code looks much cleaner. But, given what I could think off, can anyone point me to exact design pattern which deals in situations like this ?

Answer 1

There are so many ways that you can do. It's really depending on how you wanna organize your code. There are more than one good ways. If I give you vague short answers, "Abstraction", "Polymorphism", "Separation of concerns", etc. Here is one example, no if/else is required:

interface AnimalBehavior { 
    void eat(); 
    void drink();
}

abstract class Animal implements AnimalBehavior {
    abstract void eat();
    abstract void drink();
}

class Bear extends Animal  {
    void eat() {
            // bear eats cookies
    }        
    void drink() {
            // bear drinks juice
    }        
}

class Chicken extends Animal {
    void eat() {
            // chicken eats candy
    }        
    void drink() {
            // chicken drinks soda
    }
}

class AnimalStats {
    main () {
            Animal chicken1 = new Chicken();
            Animal chicken2 = new Chicken();
            Animal bear1 = new Bear();
            Animal bear2 = new Bear();

            List<Animal> animals = Arrays.asList(chicken1, chicken2, bear1, bear2);

            for(Animal animal: animals) {
                    animal.eat();
                    animal.drink();
            }        
    }
}

Answer 2

A simpler example of polymorphism:

public interface Actionable {
    void doItemAction();
}

public class Item implements Actionable {
    @Override
    public void doItemAction() {
        // insert or print
    }
}

public static void main(Actionable... args) {
    for (Actionable item : args) {
        item.doItemAction();
    }
}

You might take it a step further and extend Actionable with Insertable and Printable .