In Java, the Scanner class is part of the java.util package and is used to read input from various sources, such as the keyboard (standard input), files, and strings. It provides methods for reading different types of data, such as strings, integers, floats, and more.

Creating a Scanner Object

To use the Scanner class, you first need to import the java.util.Scanner class and create an instance of the Scanner object. You can then use various methods to read input.

import java.util.Scanner;public class ScannerExample {    public static void main(String[] args) {        // Create a Scanner object to read input from the console (System.in)        Scanner scanner = new Scanner(System.in);                // Example usage of Scanner methods    }}

Common Methods of the Scanner Class

1. Reading Input of Different Types

Scanner provides various methods to read different types of input.

• nextLine(): Reads an entire line of text.

  String name = scanner.nextLine();  // Reads a full line

• next(): Reads the next token (word) from the input. It stops at the first whitespace.

  String word = scanner.next();  // Reads the next word (token)

• nextInt(): Reads the next integer from the input.

  int number = scanner.nextInt();  // Reads an integer

• nextDouble(): Reads the next double value from the input.

  double price = scanner.nextDouble();  // Reads a double

• nextFloat(): Reads the next float value from the input.

  float weight = scanner.nextFloat();  // Reads a float

• nextBoolean(): Reads the next boolean value from the input (true or false).

  boolean isAvailable = scanner.nextBoolean();  // Reads a boolean

• nextByte(): Reads the next byte value from the input.

  byte b = scanner.nextByte();  // Reads a byte

• nextLong(): Reads the next long value from the input.

  long bigNumber = scanner.nextLong();  // Reads a long

• nextShort(): Reads the next short value from the input.

  short s = scanner.nextShort();  // Reads a short

2. Checking Input Availability

These methods help you check whether there is more input available and what type it is.

• hasNext(): Returns true if there is another token in the input.

  if (scanner.hasNext()) {    String token = scanner.next();    System.out.println(token);}

• hasNextLine(): Returns true if there is another line of input.

  if (scanner.hasNextLine()) {    String line = scanner.nextLine();    System.out.println(line);}

• hasNextInt(): Returns true if the next token can be interpreted as an integer.

  if (scanner.hasNextInt()) {    int number = scanner.nextInt();    System.out.println(number);}

3. Delimiters

You can change the default delimiter (whitespace) used by the Scanner. By default, the Scanner uses whitespace to separate tokens. You can change the delimiter using the useDelimiter() method.

• useDelimiter(String pattern): Sets the delimiter for separating tokens.

  scanner.useDelimiter(",");  // Use comma as the delimiter

4. Skipping Input

• skip(String pattern): Skips input that matches the given regular expression.

  scanner.skip("\\s*");  // Skips all whitespace characters

5. Closing the Scanner

It’s important to close the Scanner object once you're done using it to free up resources.

scanner.close();

Example Usage

import java.util.Scanner;public class ScannerMethodsExample {    public static void main(String[] args) {        // Create a Scanner object        Scanner scanner = new Scanner(System.in);                // Example: Reading a String        System.out.print("Enter your name: ");        String name = scanner.nextLine();                // Example: Reading an integer        System.out.print("Enter your age: ");        int age = scanner.nextInt();                // Example: Reading a double        System.out.print("Enter your height: ");        double height = scanner.nextDouble();                // Display the inputs        System.out.println("Name: " + name);        System.out.println("Age: " + age);        System.out.println("Height: " + height);        // Close the scanner to free up resources        scanner.close();    }}

Output Example:

Enter your name: JohnEnter your age: 25Enter your height: 5.9Name: JohnAge: 25Height: 5.9

Summary of Common Scanner Methods

Let me know if you'd like further examples or clarification on any specific Scanner methods!