Question

What's wrong with the following program?public class SomethingIsWrong { public static void main(String[] args) { Rectangle myRect; myRect.width = 40; myRect.height = 50; System.out.println("myRect's area is " + myRect.area()); } }a) Missing import statement for Rectangle class b) Incorrect usage of the Rectangle class c) Incorrect syntax for declaring myRect variable d) Missing return statement in the area() method of Rectangle class

Answer 1

The error in the program is that the Rectangle object myRect is declared but not instantiated before being used. To fix the error, the object must be instantiated with the 'new' keyword before its usage. Hence the answer is b) Incorrect usage of the Rectangle class.

Step-by-step explanation:

The problem with the given program, public class SomethingIsWrong, is the incorrect usage of the Rectangle class. Specifically, the variable myRect for the Rectangle object is declared but not instantiated before being used which results in a NullPointerException. To fix this issue, you need to instantiate the object with the new keyword before you attempt to use it:

Rectangle myRect = new Rectangle();

The answer is option b) Incorrect usage of the Rectangle class.

To correctly use the Rectangle class, you need to instantiate an object of the class using the 'new' keyword. In the code, 'Rectangle myRect;' only declares the variable but doesn't allocate memory for an object, causing a NullPointerException when trying to set the 'width' and 'height' properties. The correct code should be:

Rectangle myRect = new Rectangle();

myRect.width = 40;

myRect.height = 50;

System.out.println("myRect's area is " + myRect.area());

Learn more about Incorrect usage of Rectangle class