Java Scanner Class

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Java's Scanner class from the java.util package functions as a text parsing tool which can read input from multiple sources such as keyboard input (System.in), files or strings.

Syntax:

 import java.util.Scanner;

Creating a Scanner Object

Scanner scanner = new Scanner(System.in);

For reading from a file:

Scanner scanner = new Scanner(new File("input.txt"));

For reading from a string:

Scanner scanner = new Scanner("Hello World 123");;

Reading Input (From Console)

Read a Full Line

System.out.print("Enter a sentence: ");
String line = scanner.nextLine();

Read a Single Word

System.out.print("Enter a word: ");
String word = scanner.next();

Read an Integer

System.out.print("Enter an integer: ");
int number = scanner.nextInt();

Read a Double

System.out.print("Enter a decimal number: ");
double decimal = scanner.nextDouble();

Example

import java.util.Scanner;

public class ScannerExample {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter your name: ");
        String name = scanner.nextLine();

        System.out.print("Enter your age: ");
        int age = scanner.nextInt();

        System.out.print("Enter your height in meters: ");
        double height = scanner.nextDouble();

        System.out.println("\n--- User Details ---");
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("Height: " + height + " m");

        scanner.close(); // Always close the scanner
    }
}
Method Description
next() Reads a single word (ends on space)
nextLine() Reads a whole line
nextInt() Reads an int
nextDouble() Reads a double
nextBoolean() Reads a boolean
hasNext() Checks if more input is available
hasNextInt() Checks if next input is an integer
close() Closes the scanner (recommended)
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