asked on

child constructor and parent constructor, overriding and overloading

Hi,

I am running my code as below

public class Child extends Parent{
    public Child(int i) {
		// TODO Auto-generated constructor stub
    	System.out.println("in Child constructor");
	}

	public static void main(String[] args) {
		Child ch = new Child(4);
        ch.print();
    }
}

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public class Parent{
    protected int number = 9;

    public Parent() {
    	System.out.println("in Parent no arg construcot");
        this.number = 11;
    }

    public Parent(int number) {
    	System.out.println("in Parent arg construcot");
        this.number = number;
    }

    protected void print() {
        System.out.print(number);
    }
}

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when i run child class as java application i got below output
in Parent no arg construcot
in Child constructor
11

My question is since i am calling arument construcor of child as below
Child ch = new Child(4);

Am i not supposed to be called parent arg constructor (rather it is calling parent no argument constructor) . please advise.

i expected instead below output

in Parent no arg construcot
in Parent arg construcot
in Child constructor
11

SOLUTION

Jeffrey Dake

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SOLUTION

Guy Hengel [angelIII / a3]

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ASKER CERTIFIED SOLUTION

CPColin

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gudii9

ASKER

public class Parent{
    protected int number = 9;

    public Parent() {
    	System.out.println("in Parent no arg construcot");
        this.number = 11;
    }

    public Parent(int number) {
    	System.out.println("in Parent arg construcot");
        this.number = number;
    }

    protected void print() {
        System.out.print(number);
    }
}

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public class Child extends Parent{
    public Child(int i) {
		// TODO Auto-generated constructor stub
    	super(4);
    	System.out.println("in Child constructor");
	}

	public static void main(String[] args) {
		Child ch = new Child(4);
        ch.print();
    }
}

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above gave below output

in Parent arg construcot
in Child constructor
4

which makes sense

gudii9

ASKER

is there is a way i can see below kind of output

in Parent no arg construcot
in Parent arg construcot
in Child constructor
4

Basically i wan to see parent no arg as well arg constructors?

public class Child extends Parent{
    public Child(int i) {
		// TODO Auto-generated constructor stub
    	super();
    	super(4);
    	System.out.println("in Child constructor");
	}

	public static void main(String[] args) {
		Child ch = new Child(4);
        ch.print();
    }
}

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if i write as aboave getting below error at line 5
Constructor call must be the first statement in a constructor

please advise

Jeffrey Dake

No only one constructor is called at the parent class level. If you really need tha kind of functionality, I would create a new function that you call within the constructor. While you can only call one super call in your child class, immediately after you could call the function you declared in the parent class.