core24UserInput

1package pkg1core;2 3/*4 * core24UserInput.java5 * ----------------6 * Reading user input with Scanner and BufferedReader.7 *8 * EXPLANATION:9 *  - Scanner: easy token-based parsing (nextInt, nextLine). Good for learning.10 *  - BufferedReader + InputStreamReader: faster for large text; readLine() per line.11 *  - Pitfall: mixing nextInt() then nextLine() without consuming the leftover newline.12 */13import java.io.BufferedReader;14import java.io.InputStreamReader;15import java.util.Scanner;16 17public class core24UserInput {18 19    static void demoScanner() {20        // Simulated input via String — same API as System.in21        Scanner sc = new Scanner("Alice\n25\n3.14\n");22        System.out.println("Scanner demo:");23        System.out.println("  name: " + sc.nextLine());24        System.out.println("  age:  " + sc.nextInt());25        sc.nextLine(); // consume newline after nextInt before next nextLine26        sc.close();27    }28 29    static void demoBufferedReader() throws Exception {30        String simulated = "line one\nline two\n";31        BufferedReader br = new BufferedReader(new InputStreamReader(32                new java.io.ByteArrayInputStream(simulated.getBytes())));33        System.out.println("BufferedReader demo:");34        System.out.println("  " + br.readLine());35        System.out.println("  " + br.readLine());36        br.close();37    }38 39    public static void main(String[] args) throws Exception {40        demoScanner();41        demoBufferedReader();42 43        // Real interactive use (uncomment to try):44        // Scanner in = new Scanner(System.in);45        // System.out.print("Enter your name: ");46        // String name = in.nextLine();47        // System.out.println("Hello, " + name);48    }49}