Question

Write a method minimum3 that returns the smallest of three floatingpoint numbers. Use the Math.min method to implement minimum3. Incorporate the method into an application that reads three values from the user, determines the smallest value and displays the result.

Short answer

The minimum3 method uses Math.min twice to find the smallest of three numbers, and the main method reads inputs from the user, invokes minimum3, and displays the smallest number.

Step-by-step solution

Create the minimum3 Method

Define a method called minimum3 that takes three double parameters. Use the Math.min method twice to determine the smallest of the three numbers. First, find the smaller of the first two numbers, and then compare the result with the third number to find the smallest among all three.

Set Up User Input

In the application's main method, create a Scanner object to read user input. Prompt the user for three floating-point numbers and store these inputs in three separate variables.

Invoke minimum3 and Display Result

Call the minimum3 method with the three user input values as arguments. Store the returned smallest value in a variable and display it to the user with an appropriate message indicating it is the smallest value.

Key concepts

Floating-Point Number Comparison

Comparing floating-point numbers in Java, or in any programming language for that matter, can be surprisingly tricky. This is because these numbers are represented in a binary format that can't exactly represent all decimal values, leading to potential rounding errors. When using the Math.min method to find the smallest number, Java handles this comparison reliably for you.

For comparing two double values, Math.min will return the one that is numerically lower than the other. However, if both numbers are exactly equal, the method returns the first argument. Special care is needed when dealing with NaN (Not a Number) values, since any comparison involving NaN returns false, and Math.min will return NaN if either of the arguments is NaN.

minimum3 Method Implementation

To create a method that finds the minimum of three floating-point numbers using Java's Math.min method, you'll need to compare pairs of numbers sequentially. The minimum3 method will take three double parameters:

public static double minimum3(double num1, double num2, double num3) { double firstMin = Math.min(num1, num2); return Math.min(firstMin, num3);}

Using Math.min method twice allows you to break down the comparison into two steps. Initially, you find the smaller value between the first two arguments, and then you compare this intermediate result with the third argument, ultimately giving you the smallest value of all three.

Java Scanner Class

The Java Scanner class is a simple text scanner which can parse primitive types and strings using regular expressions. It breaks its input into tokens using a delimiter pattern, which by default matches whitespace.

For reading user input, especially in console applications, the Scanner is particularly useful. You create a Scanner object by passing a System.in stream in its constructor like so:

Scanner scanner = new Scanner(System.in);

Once you have a Scanner instance, you can prompt the user and then read different kinds of input - in the case of our minimum3 method, you will be reading in floating-point numbers with scanner.nextDouble(). It's crucial to handle potential exceptions that arise when the input does not match the expected data type.

User Input Handling

Handling user input is a fundamental part of many applications. There are a few things to keep in mind when doing so to provide a good user experience and avoid errors in your application:

• Always prompt the user clearly for the input you expect them to provide.
• Use try-catch blocks to handle exceptions that occur when input does not match the expected type, or when input is out of range.
• After processing the input, give clear feedback to the user. If they input three floating-point numbers, for example, you will display the smallest one back to them with a meaningful message.

Implementing proper input validation and error handling ensures your application is robust and user-friendly.