Inheritance in Java (design pattern)

Question

I'm refactoring some code, abstracting functionality from a subclass to a helper class, but I found that I need methods from the superclass in the helper class.

I was wondering if there is a design pattern that can help me to do this. Or any other suggestions.

public class Notification(){
    public void printMessage(String k, String str){
        //Some code
    }
}

public class NotificationImpl1 extends Notification(){
    ErrorHelper helper = new ErrorHelper();
    helper.showMessage("test");
}

public class ErrorHelper(){
    public void showMessage(String msg){
        // need to call printMessage() here
    }
}

Thanks in advance.

a possible solution is to declare the subclass Error helper outside of NotificationImpl1 and just add extends Notification to class ErrorHelper this would give you access to all the functionality of the parent, or if it is just a small amount of code just copy and paste the method you need. — user3458225
– user3458225, Commented Nov 25, 2016 at 3:35

Jude Niroshan · Accepted Answer · 2016-11-25 05:35:37Z

2

public class ErrorHelper(){

  Notification notification = null;

  public ErrorHelper(Notification notification){
    this.notification = notification;
  }

  public void showMessage(String k_str, String msg){
    this.notification.printMessage(k_str, msg);
    // need to call printMessage() here
  }
}

edited Nov 25, 2016 at 5:35

answered Nov 25, 2016 at 3:28

Jude Niroshan

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1 Comment

user3458225 Over a year ago

I also agree with this solution.

Henry · Accepted Answer · 2016-11-25 04:00:55Z

0

public class Notification(){
   public void printMessage(String k, String str){
      //Some code
   }
}

public class NotificationImpl1 extends Notification(){
     public void method1() {
          ErrorHelper helper = new ErrorHelper();
          helper.showMessage("test", this);
     }
}

public class ErrorHelper() {
    public void showMessage(String msg, Notification notification){
       // Change msg to necessary 2 parameters.
       String k = getK(msg);
       String str = getStr(msg);
       notification.printMessage(k, str);
    }
}

answered Nov 25, 2016 at 4:00

Henry

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