Java alternative to multiple inheritance

Question

Since I know Java doesn't support multiple inheritance, I'd like to know how could I implement this design in Java:

Class StudentModel extends BaseModel{
   public void doSomething(){};
}
Class ParentModel{
   protected List<BaseModel> children = new List<BaseModel>();
   public void addChild(BaseModel child){
      children.add(child);
   }
   // and other parent-children related functionality
}

Class ConcreteParentModel{
    // should contain both StudentModel and ParentModel functionalily
}

Thanks!

You can implement multiple interfaces, but only extend a single class. — OneCricketeer
– OneCricketeer, Commented Oct 29, 2015 at 20:19
You can always use composition instead of inheritance. Just make ConcreteParentModel have a parent and a student and have wrapper methods that pass the call to the appropriate instance variable. — azurefrog
– azurefrog, Commented Oct 29, 2015 at 20:20
What I aim to achieve is just less code. Implementing interfaces wouldn't do the job. I'll have to implement parent-related methods for every other class that also should be a "parent". Also a wrapper wouldn't do the job since i'll have to write the wrapper code for every derived class that should also be a parent. — Forepick
– Forepick, Commented Oct 29, 2015 at 20:31
If you want to write less code, use a language designed for that purpose - there are other languages on the JVM that may interest you. Java (the language) is designed for clean and robust code, not short code. — Gimby
– Gimby, Commented Oct 29, 2015 at 21:22

Michael Queue · Accepted Answer · 2015-10-29 20:28:06Z

2

You should use an adapter pattern

In software engineering, the adapter pattern is a software design pattern that allows the interface of an existing class to be used from another interface. It is often used to make existing classes work with others without modifying their source code.

answered Oct 29, 2015 at 20:28

Michael Queue

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4 Comments

Forepick Over a year ago

Thanks, but this would not help me to end with less code. I plan to add more other concrete classes that derive from other classes but all have this "parent" functionality.

Michael Queue Over a year ago

Ok. I would implement a combination of adapters and strategy patterns then. In Strategy pattern, we create objects which represent various strategies and a context object whose behavior varies as per its strategy object. The strategy object changes the executing algorithm of the context object.

Forepick Over a year ago

I'm afraid this wouldn't help as well. I need all the inherited methods to be visible for Jackson via @JsonProperty

Michael Queue Over a year ago

Unfortunately your only real solution is to use adapters.

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