Question

Write and run a Java program that inputs three names and print them in their alphabetical order.

Short answer

Write a Java program using `Scanner` to input three names, sort them using `Arrays.sort()`, and print them.

Step-by-step solution

Set Up the Java Program

Start by creating a new Java file named `SortNames.java`. Import necessary classes for input handling.

Import Scanner for Input

Add the line `import java.util.Scanner;` at the beginning of your code to import the Scanner class, which will be used to gather user input.

Create the Main Class and Method

Define the main class with `public class SortNames`, and then add the `main` method using `public static void main(String[] args)`.

Initialize the Scanner

Inside the main method, initialize the Scanner object using `Scanner scanner = new Scanner(System.in);` to take input from the user.

Prompt for Name Inputs

Prompt the user to input three names. Use `System.out.println("Enter first name:");`, `System.out.println("Enter second name:");`, and `System.out.println("Enter third name:");` for guidance.

Store Names in an Array

Declare and initialize an array to store the names. Use `String[] names = new String[3];` and store each name using `names[0] = scanner.nextLine();`, and so on, for all three inputs.

Sort the Array

Utilize the `Arrays.sort()` method to sort the names alphabetically. Make sure to include this by adding `import java.util.Arrays;` at the top of the file and then call `Arrays.sort(names);`.

Print Sorted Names

Iterate through the sorted array using a for-each loop and print each name to the console using `System.out.println(name);` inside the loop.

Close the Scanner

Close the scanner using `scanner.close();` to prevent resource leaks.

Test the Program

Run the program and test by entering different sets of three names to ensure they are printed in alphabetical order.

Key concepts

Java I/O handling

Java I/O (Input and Output) handling is a crucial part of programming, as it allows a program to interact with users and other systems by getting and providing information. In Java, the `Scanner` class is commonly used for simple console-based input. To use this class, you need to include `import java.util.Scanner;` at the top of your program. This makes the functionalities of the Scanner class accessible, enabling you to read various data types from different input sources, most often from the keyboard. When you create a `Scanner` object, you can utilize methods such as `nextLine()` to read a full line of input. This is especially useful for inputs that contain spaces, like names. Always ensure that you close the scanner using `scanner.close();` once you are done taking inputs. This step is essential to free up system resources and prevent resource leaks. Nonetheless, it's vital to understand that Scanner is mostly suited for console applications and has some limitations in performance when dealing with large volumes of data.

• Import the necessary I/O classes at the beginning of your code.
• Create and initialize the I/O handling objects inside your method.
• Properly close I/O resources to maintain system performance and stability.

Array sorting in Java

Sorting is a fundamental operation in programming, and Java provides robust tools to perform sorting operations easily. Arrays, being a fundamental data structure in Java, can store multiple values of the same type in a convenient manner. To sort an array, Java provides the `Arrays.sort()` method, which is part of the `java.util.Arrays` class that you need to import using `import java.util.Arrays;`. This method automatically sorts the elements of the array in ascending order. When you apply this function to an array of strings, the strings are arranged in alphabetical order based on Unicode values. Sorting arrays can be particularly useful for organizing data, searching, and creating efficient algorithms. While `Arrays.sort()` is fine for most simple operations, complex applications might require custom sorting algorithms or using collections such as `ArrayList` which have more flexible sorting and manipulation capabilities.

• Import `Arrays` class to enable sorting capabilities.
• Use `Arrays.sort()` to arrange elements in the desired order.
• Consider custom solutions for unique sorting requirements beyond basic capabilities.

Java classes and methods

In Java, organizing your code using classes and methods is crucial for maintaining a clear, efficient, and reusable codebase. Java encourages object-oriented programming (OOP) principles, which means classes and objects come to the forefront most of the time. A Java program typically starts with defining a class, which is a blueprint for creating objects. A standard class designates a name and can contain fields, constructors, and methods. For instance, in the example process, `public class SortNames` defines a class that serves as the container for the program. Within a class, the `main` method specifically acts as the entry point for execution. It's defined using `public static void main(String[] args)` which allows the JVM (Java Virtual Machine) to understand where to begin. Methods are blocks of code designed to perform a specific task and can be invoked with or without parameters. They help in avoiding code duplication and enhancing modularity and readability. Defining methods within your classes helps to break down logic into manageable chunks and clarify program structure for future maintenance.

• Use classes to encapsulate related data and behavior.
• Define methods for task-specific operations within classes.
• Utilize the `main` method as the starting point of your Java application.