CODEWITHSUNDEEP
javainheritanceconstructor
user2924118
user2924118

Reputation: 1

Java: Constructor of a subclass has an Object of parent class

I'm learning Java at school and I have encountered a problem with inheritance and constructors. I have 3 classes, Class A, Class B and Class C. Class A is the superclass, Class B extends class A and Class C extends Class B. Class B has a constructor whose formal(parameter) is a String. All good till here. So now, I extend Class B to Class C. In Class C I need to create a constructor that has an instance of Class B as its parameter. I then need to extract some information from Class B and store that in Class C.

Here is the code we have.

public class B extends A {

int b;

public B(int b) {
this.b=b;
}

}

public class C extends B {

int c;

public C(B b) {

this.c = b.b;

}

}

In my main()

I have the following line of code to create an instance of C

C c_c = new C(new B(12));

When this is compiled, I get an error. error: constructor B in class B cannot be applied to given types;

reason: actual and formal argument lists differ in length

Would you guys be able to help me understand what I've done wrong?

Upvotes: 0

Views: 788

Answers (2)

Evgeniy Dorofeev
Evgeniy Dorofeev

Reputation: 136002

You dont need to reload information from B to C. Simply make B's fields visible to C eg make them protected

Upvotes: 0

Iswanto San
Iswanto San

Reputation: 18569

You must explicitly call B's constructor from C's constructor since no default constructor defined in class B

public C(B b) {
   super(0);
   this.c = b.b;
}

Upvotes: 2

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