CODEWITHSUNDEEP
springinheritancetemplate-method-pattern
adolzi
adolzi

Reputation: 691

Inheritance: main method in parent class with relation to specific implementation of a few methods in child

I need to implement two similar processes which basicaly do the same logic but a few parameters/methods may differ. I'm wondering if it would be a good practice to extract the main logic to a parent class and specify a result of a few methods to child classes. Something like:

abstract class Parent{

protected CommonDao commonDao;

protected String specStatus;

protected abstract int getDbResult();

public Parent(CommonDao commonDao){
    this.commonDao = commonDao;
}

public String mainLogic(){
    if(commonMethod()){
    //..
    }
    int specDbResult = getDbResult();
    //some logic here

    return specStatus;
}

private boolean commonMethod(){ 
//.. 
return true;
}

}

@Service
public Child1 extends Parent(){

  @Autowired
  public Child1(CommonDao commonDao){
     super(commonDao);
     super.specStatus = specStatus1;
  }

  @Override
  protected String getDbResult(){
      commonDao.getResult1();
  }

}

@Service
public Child2 extends Parent(){

  @Autowired
  public Child2(CommonDao commonDao){
     super(commonDao);
     super.specStatus = specStatus2;
  }

  @Override
  protected String getDbResult(){
      commonDao.getResult2();
  }

}

If it doesn't seem to be a clean code, what solution would you recommend in such case? Thanks in advance

Upvotes: 1

Views: 169

Answers (1)

inquirymind
inquirymind

Reputation: 155

Using Dependency Injection, composition seems clearly a better approach that inheritance

And dao as an attribute is not enough for a parent child relationship

Please make sure you have understood Item 16 of Effective Java, as any programmer might http://thefinestartist.com/effective-java/16

EDITED as requested:

@Service
public class NotAChild{

@Autowired
CommonOps1 commonOps1;

@Autowired
CommonOps2 commonOps2;

private boolean commonMethod(){ 
int result1 = commonOps1.getDbResult(); 
int result2 = commonOps2.getDbResult(); 
....
return result1 + result2;
}
}

@Component
public class CommonOpS1{

@Autowired
CommonDao commonDao;

protected String getDbResult(){
      commonDao.getResult1();
}

}

@Component
public class CommonOpS2{

@Autowired
CommonDao commonDao;

protected String getDbResult(){
      commonDao.getResult2();
}

}

All other NotAChildN objects can use the common methods of CommonOps.

So, you won't use inheritance

Upvotes: 0

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