Java Interface Quiz

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Question: 1 2 3 4 5 6

Question One

A class can implement more than one interface?

True False

A class can extend an interface?

True False

An interface can extend an interface?

True False

Interfaces can have constructors?

True False

All members of an interface are public by default?

True False

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Question Two

Why would you use an abstract class over an interface?

Can provide additional methods with code already implemented
You have multiple subclasses which need to perform the smae implementation of a task
Both of the above

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Question Three

  interface A {

    final int k = 8;               // Line 1

    private int m;                 // Line 2

    public void aMethod();         // Line 3

    String fun(Char s);            // Line 4

  }

  

Which line will cause an error?

Line 1
Line 2
Line 3
Line 4

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Question Four

  interface A {

    void go();

  }

  Class B {

    public void go() {

      System.out.println("GO!");
    
    }

  }

  Class C extends B implements A {}

  Class Main {

    publci static void main(String[] args) {

      A a = new C();
      a.go();

    }

  }

  

What is printed out?

result=

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Question Five

  interface A {

    int n = 111;

  }

  Class B implements A {

    void inc() {

      n++;

    }

  }

  

Will this compile?

True False

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Question Six

  interface ABC {

    void methodOne();

  }

  interface PQR extends ABC {

    void methodTwo(int i);

  }

  abstract class XYZ implements PQR {

    public void methodOne() {

      methodTwo(2);

    }

  }

  class EFG extends XYZ {

    public void methodTwo(int i) {

      System.out.println(Math.pow(i, 2))

    }

  }

  class Main {

    public static void main(String[] args) {

      ABC abc = new EFG();
      abc.methodOne();

    }

  }

  

What is printed?

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