Reading User Input (Scanner)

The `Scanner` class provides different methods for reading data types:

• `nextInt()`: Reads the next integer tokens.
• `nextDouble()`: Reads decimal tokens.
• `next()`: Reads a single word token (stops at spaces).
• `nextLine()`: Reads an entire line of text including spaces.

⚠️ Critical Gotcha: The Newline Buffer Issue
When you input a number and press Enter (e.g. `nextInt()`), Java reads the number token but leaves the trailing newline character (`\n`) sitting in the buffer. If you subsequently call `nextLine()`, it instantly consumes that leftover newline and returns empty text without waiting for user input. To fix this, always call a dummy `scanner.nextLine()` to "flush" the buffer after reading numbers before reading strings.

Let's run a program that reads name, age, and details safely with proper buffer flushes:

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        // Setup scanner reading standard input stream
        Scanner scanner = new Scanner(System.in);
        
        System.out.print("Enter your Age: ");
        int age = scanner.nextInt();
        
        // 🚨 CRITICAL: Flush the newline character from the buffer!
        scanner.nextLine(); 
        
        System.out.print("Enter your Full Name: ");
        String name = scanner.nextLine();
        
        System.out.println("Hello, " + name + "! You are " + age + " years old.");
        
        // Good practice: Close the resource streams
        scanner.close();
    }
}