Question

Write the statement that you must put before any other code to tell the compiler that you will be using the Scanner class.

Short answer

Use `import java.util.Scanner;` to use the Scanner class.

Step-by-step solution

Identify the Package

To use the Scanner class in Java, you must first identify which package it belongs to. The Scanner class is part of the "java.util" package.

Import the Package

Once you know the package, the next step is to write an import statement at the beginning of your Java file to include the Scanner class. The correct import statement is: ```java import java.util.Scanner; ``` This statement allows you to use the Scanner class to take input from users in your program.

Key concepts

Scanner class

The Scanner class in Java is a powerful tool used to read and parse various types of input. It's mainly utilized for handling input from users during program execution. This class can process different input types like strings, integers, and doubles, which makes it a versatile choice for input handling.

Java programs often use the Scanner object to read data from the console. Here's how you can declare and initialize a Scanner object:

• First, create an instance of Scanner by using the `new` keyword.
• You need to pass `System.in` as an argument, which tells the Scanner to read input from standard input (usually the keyboard).

Setting up a Scanner object looks like this: ```java Scanner input = new Scanner(System.in); ``` Once the Scanner object is created, you can call methods like `nextInt()`, `nextLine()`, or `nextDouble()` to read different types of data.
Do not forget to close the Scanner object after its usage to free up system resources. You can do this by calling `input.close()`. This step is essential as it prevents potential resource leaks.

java.util package

In Java, the `java.util` package is a core package used extensively in Java applications. This package provides a large collection of utility classes that facilitate various tasks in a Java program, such as handling dates, working with random numbers, and collections like lists and maps.

One of the key features of this package is its inclusion of classes that deal with data manipulation. Some commonly used classes within the `java.util` package are:

• Scanner - for input handling.
• ArrayList - a resizable array implementation.
• HashMap - used for storing key-value pairs.

The package is so crucial because it provides developers with pre-built, optimized tools that save time and effort during the development process. To use these classes, you need to import them at the start of your Java file using the `import` keyword.
Each class is imported from this package, including the widely used Scanner class, like this: ```java import java.util.Scanner; ```
This tells the compiler to reference the necessary classes for your code.

Java input handling

Java offers a variety of mechanisms to handle input, but the Scanner class is one of the most commonly used methods due to its simplicity and ease of setup. Handling input effectively is crucial for creating interactive and dynamic applications. Here's why:

• It allows applications to respond to users' actions by receiving input and processing it accordingly.
• Supports multiple data types, making it flexible for different scenarios.

For example, if you write a program that needs a user's name and age, you can use the Scanner class to read string and integer inputs, respectively.
Integrating input handling in Java requires these steps:

• First, initialize a Scanner instance to handle input.
• Use various Scanner methods like `next()`, `nextInt()`, or `nextLine()` to capture inputs appropriately.
• Finally, always remember to close the Scanner object with `Scanner.close()` when you're done.

This ensures that your program can effectively handle inputs without leaving unused resources open, leading to cleaner and more efficient Java applications.