Question

Write an application that reads five integers and determines and prints the largest and smallest integers in the group. Use only the programming techniques you learned in this chapter.

Short answer

Initialize two variables with max and min possible integer values, read five integers from the user, update the variables as needed, and then print the smallest and largest values.

Step-by-step solution

Setup the programming environment

Assuming the programming language being used is Java, begin by creating a class named 'MinMaxFinder' and a main method. Import the Scanner class which will be used to read input from the user.

Initialize variables and create a Scanner instance

Inside the main method, declare two integer variables to store the smallest and largest numbers, initializing the smallest to Integer.MAX_VALUE and the largest to Integer.MIN_VALUE. Then, create a Scanner object to read the integers from the user.

Read integers using a loop

Use a for loop to iterate five times. Inside the loop, prompt the user to enter an integer and use the Scanner object to read the next integer input. Within each iteration of the loop, compare the current input with the existing values of the smallest and largest variables.

Check for the smallest integer

Within the loop, if the current integer input is less than the value of the smallest variable, update the smallest variable with the current integer's value.

Check for the largest integer

Similarly, if the current integer input is greater than the value of the largest variable, update the largest variable with the current integer's value.

Print the results

After the loop completes, print out the smallest and largest integers found from the inputs.

Close the Scanner

It’s a good practice to close the Scanner object once it is no longer needed to prevent resource leaks.

Key concepts

Java for loops

Java offers various loop structures to handle repetitive tasks efficiently. One of the most commonly used is the for loop, which is ideal for cases where you know in advance how many times you need to repeat the loop. In our integer comparison exercise, we use a for loop to iterate exactly five times, corresponding to the five integers we need to read.For example, the syntax for a for loop that runs five times can be as simple as:

for (int i = 0; i < 5; i++) { // code to repeat }

• The first part int i = 0 initializes a counter variable.
• The second part i < 5 sets the condition for the continuation of the loop.
• The third part i++ updates the counter after each iteration.

Always ensure the loop's body, the code between the braces { }, contains the logic you need to repeat. In this case, our loop contains the logic for reading integers from the user and comparing them to find the smallest and largest values. Efficient use of for loops can make your code cleaner and easier to understand, ensuring better manageability.

Java Scanner class

Input handling in Java is a critical task when creating interactive applications. The Java Scanner class is part of the java.util package and provides convenient methods to read different types of input, including integers, strings, and other data types from various sources like the keyboard, files, and streams. In our integer comparison exercise, we use the Scanner to read user input from the console.To use the Scanner, you first need to import it with:import java.util.Scanner;Then instantiate it to read from the standard input stream, usually the keyboard:Scanner scanner = new Scanner(System.in);Use the nextInt() method to read an integer:int number = scanner.nextInt();It is good practice to close the scanner with scanner.close(); when you're done using it to prevent resource leaks. With the Scanner class, you can simplify user input operations in Java and efficiently collect the data you need for processing.

Integer.MAX_VALUE and Integer.MIN_VALUE

In Java, every data type has limits to the values it can hold. For the int type, these bounds are defined by Integer.MAX_VALUE and Integer.MIN_VALUE. The former represents the maximum positive value an int can store, which is \(2^{31} - 1\), and the latter represents the smallest negative value, \( -2^{31}\).In our exercise, these constants are used as starting points for finding the largest and smallest integers in a series of inputs. We initialize our 'smallest' variable with Integer.MAX_VALUE since any value that the user enters will be less than or equal to this value. Similarly, we start our 'largest' variable with Integer.MIN_VALUE as any input by the user will be greater than or equal to this value. With these initializations, we are setting our variables to extremes that are guaranteed to be updated once user inputs are processed.Understanding these constants is critical not only to solve our integer comparison exercise but also in handling edge cases where integer overflows or underflows may occur, affecting the correctness of the program. Therefore, it is essential to be aware of these bounds while dealing with integer calculations and comparisons in Java.