Question

A class weight is having a data member pound, which will have the weight in pounds. Using a conversion function, convert the weight in pounds to weight in kilograms which is of double type. Write a program to do this. 1 pounds \(=1 \mathrm{~kg} / 0.453592\) Use default constructor to initial assignment of 1000 pounds.

Short answer

Define a `Weight` class with 1000 pounds and a conversion function to kilograms.

Step-by-step solution

Understand the Problem Requirements

We need a class named `weight` that has a data member called `pound` to store weight in pounds. Using a constructor, this should be initially set to 1000 pounds. We have to create a conversion function within this class that converts the weight from pounds to kilograms.

Define the Class and Data Members

Define a class `Weight` with a private data member, an integer, `pound`. This is where the current weight in pounds will be stored.

Implement the Default Constructor

Create a constructor for the class `Weight`. This default constructor will set the initial value of `pound` to 1000.

Implement the Conversion Function

Within the `Weight` class, define a public method named `convertToKilograms`. This function will convert the stored `pound` value to kilograms using the conversion factor 1 pound = 1 kg / 0.453592, and return the result as a double.

Bring It all Together

Write out the full code for the `Weight` class by using a compiler-friendly language, such as C++ or Java, with the elements defined in the previous steps. Use the conversion factors as constants within the class.

Key concepts

Class Definition

A class in Java is essentially a blueprint for creating objects. It defines a data structure, encompassing both data and methods, that can model real-world entities. For our exercise, we need to define a class called `Weight`. In Java, defining a class starts with the `class` keyword, followed by the class name. Inside the class, we can declare data members and methods.
A class can contain:

• Data Members: Variables to hold data.
• Methods: Functions to perform operations.

In our context, we have to include a data member `pound` and methods for conversion in our class. This approach promotes better organization and reuse of code in Java programming.

Default Constructor

A default constructor in Java is a special method used to initialize objects. It has the same name as the class and does not have a return type. Every time an object of the class is created, the constructor runs automatically.
In our `Weight` class, the default constructor must set the initial weight in pounds to 1000. This means that upon creating an instance of the `Weight` class, our object is automatically set up with 1000 pounds without additional input. Constructors are crucial because they ensure that an object is in a valid state from the start.

Data Conversion

Data conversion is the process of transforming data from one type to another. In our exercise, this involves converting a weight value from pounds (an integer) to kilograms (a double). This is essential because pounds and kilograms represent weights in different measurement systems.
A conversion function is needed to perform this operation accurately. Our method `convertToKilograms` will take the `pound` value and apply a conversion factor—1 pound = 1 kg / 0.453592. This factor changes the value from one scale to another, giving an accurate kilogram measurement as a double.

Data Member

A data member in Java is a variable that belongs to a class. It holds the data specific to an object. In the `Weight` class, `pound` is a data member that stores the weight in pounds. Data members can have different access controls, determining how other parts of the program can use them. Typically, they are private to protect the integrity of the data.
The key roles of data members include:

• Storing Values: Keep essential attributes of objects.
• Encapsulation: Restrict access to sensitive data.

By managing data through data members, we ensure that our Java classes are both effective and safe for data handling.

Pound to Kilogram Conversion

Converting from pounds to kilograms is a common task in programming when dealing with weights. In this exercise, we use a specific conversion factor. Knowing that 1 pound is equivalent to 1 kg divided by 0.453592 helps convert correctly.
For example, if we have a weight of 1000 pounds, the conversion to kilograms involves multiplying by the reciprocal of 0.453592:\[\text{Kilograms} = \text{Pounds} \times \left(\frac{1}{0.453592}\right)\]This calculates the respective weight in kilograms with high precision, which is often required in scientific computations.