Computer scienceProgramming languagesJavaCode organizationObject-oriented programmingClass hierarchiesBuilding class hierarchies

Runtime type checking

Theory

Counting 2D shapes

Report a typo

Below is a part of a class hierarchy consisting of a lot of classes:

class Shape { }

class Shape2D extends Shape { }

class Shape3D extends Shape { }


class Circle extends Shape2D { }

// ...  classes which extends Shape2D


class Cube extends Shape3D { }

// ...  classes which extends Shape3D

Implement a method that takes an array of shapes and counts how many objects of classes that extend Shape2D the array contains. Do not count objects of Shape2D, only its subclasses.

Write a program in Java 17
class Counter {
public static int count2DShapes(Shape[] shapes) {
return 0;
}
}

// Don't change the code below

class Shape {
}

class Shape2D extends Shape {
}

class Shape3D extends Shape {
}


class Circle extends Shape2D {
}

class Shape2DSub1 extends Shape2D {
}

class Shape2DSub2 extends Shape2D {
}


class Cube extends Shape3D {
}

class Shape3DSub1 extends Shape3D {
}

class Shape3DSub2 extends Shape3D {
}
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