Is it OK to call abstract method from constructor in Java? [duplicate]

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This code demonstrates why you should never call an abstract method, or any other overridable method, from a constructor:

abstract class Super {
    Super() {
        doSubStuff();
    }
    abstract void doSubStuff();
}

class Sub extends Super {
    String s = "Hello world";

    void doSubStuff() {
        System.out.println(s);
    }
}

public static void main(String[] args) {
    new Sub();
}

When run, this prints null. This means the only “safe” methods to have in a constructor are private and/or final ones.

On the other hand, your code doesn’t actually call an abstract method from a constructor. Instead, you pass an uninitialized object to another thread for processing, which is worse, since the thread you’re starting may be given priority and execute before your Base finishes its initialization.

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