How to force a Constructor to be defined in all subclass of your abstract class in java

How to force a Constructor to be defined in all subclass of your abstract class in java

In Java, you can force all subclasses of your abstract class to define a constructor by declaring an abstract constructor in the abstract class. When you declare an abstract constructor, all subclasses must provide their own constructor implementations that call a constructor of the superclass explicitly using the super keyword. Here's how you can achieve this:

public abstract class MyBaseClass {

    public MyBaseClass() {
        // This is the abstract constructor.
        // Subclasses must call this constructor using 'super'.
    }

    // Other abstract methods and class members can be defined here.
}

In this example:

  1. MyBaseClass is an abstract class with an abstract constructor.

  2. Subclasses of MyBaseClass must provide a constructor that calls the constructor of the superclass using the super keyword. This enforces that every subclass must initialize the base class.

Here's an example of a subclass that correctly defines a constructor:

public class MySubClass extends MyBaseClass {

    public MySubClass() {
        // Call the constructor of the superclass using 'super'.
        super();
        // Other subclass-specific constructor logic can go here.
    }

    // Other methods and members can be defined here.
}

If a subclass fails to provide a constructor that calls the superclass constructor, the Java compiler will produce an error, ensuring that all subclasses adhere to the requirement of defining a constructor.

Note that you can add parameters to the abstract constructor if needed, and subclasses must provide matching constructors with the same parameters in their definitions.

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