Enthuware

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What will be a part of the output when the following code is compiled and run?

class Boo {
    int boo = 10;
    public Boo(int k){ System.out.println("In Boo k = "+k); boo = k;}
}

class BooBoo extends Boo {
     public BooBoo(int k ){ super(k); System.out.println("In BooBoo k = "+k); }
}
    
class Moo extends BooBoo implements Serializable {
    int moo = 10;
    public Moo(){ super(5); System.out.println("In Moo"); }
}
    
public class TestClass {
    
    public static void main(String[] args) throws Exception{
    
        var moo = new Moo();
        var fos = new FileOutputStream("c:\\temp\\moo1.ser");
        var os = new ObjectOutputStream(fos);
        os.writeObject(moo);
        os.close();
        var fis = new FileInputStream("c:\\temp\\moo1.ser");
        var is = new ObjectInputStream(fis);
        moo = (Moo) is.readObject();
        is.close();    
      }
}

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1. In Boo k = 5
    In BooBoo k = 5 
2. In Boo k = 0
    In BooBoo k = 0 
3. In Moo
4. It will throw an exception at runtime.
5. It will not compile.

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While instantiating a new Moo, all the constructors will be executed. So it  will print
 In Boo k = 5
 In BooBoo k = 5
 In Moo
There will not be any problem while serializing the Moo object.
However, while deserializing, the JVM will not find any no-arg constructor that can be invoked to initialize BooBoo.
No-args constructor is required in BooBoo because BooBoo is the most specific class in the class hierarchy that doesn't implement Serializable.
So it will throw an InvalidClassException.

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var moo = new Moo()

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 In Boo k = 10
 In BooBoo k = 5