魏靖容Java內建方法length(),charAt()

w3schools編寫Java程式語言

微軟VS Code編寫Java程式語言

import java.util.Scanner; // Import the Scanner class

class MyClass {
  public static void main(String[] args) {
    String a, b="";
    Scanner myObj = new Scanner(System.in); // Create a Scanner object
    System.out.print("輸入: ");
    a = myObj.nextLine(); // Read user input
    for (int i = 0; i < a.length(); i++)
        b = a.charAt(i) + b;
      System.out.println("輸出: "+ b);
    }
}