Step by Step solution about How to resolve the algorithm Keyboard input/Obtain a Y or N response step by step in the Kotlin programming language

Explanation:

This code is a Java application that prompts the user to enter 'Y' or 'N' to confirm quitting the program. It uses the Java AWT (Abstract Window Toolkit) libraries to display a simple window and handle user input from the keyboard. Here's a detailed breakdown:

1. Imports: The code imports necessary classes from the Java library for handling window creation, keyboard input, and system operations.

2. Test Class: This class extends JFrame, which is a Swing component for creating a window. It contains:

   • Constructor (init block):
     • It clears any pending input in the standard input stream (System.in`) to prevent any interference.
     • It prompts the user to enter 'Y' or 'N' to quit the program.
     • It adds a KeyAdapter to handle keyboard input.
   • quit Method: This method is called when the user presses 'Y' to quit. It hides the window, disposes of it, and exits the program with a status code of 0.

3. main Function: This is the entry point of the program.

   • It uses SwingUtilities.invokeLater to ensure that the window creation and event handling happen in the Java Swing Event Dispatch Thread (EDT).
   • It creates an instance of the Test class (f).
   • It sets the focusability of the window to true and makes it visible.

Execution Flow:

1. The program starts and prompts the user to enter 'Y' or 'N' to quit.
2. The user presses 'Y' or 'N'.
3. The key press event is handled by the KeyAdapter in the Test class:
   • If 'Y' is pressed, the quit method is called to end the program.
   • If 'N' is pressed, a message is printed indicating that the program will end anyway.
   • If any other key is pressed, a message is printed instructing the user to only press 'Y' or 'N'.
4. The program exits when the quit method is called or when the user presses a non-valid key.

// version 1.0.6

import java.awt.event.KeyAdapter
import java.awt.event.KeyEvent
import javax.swing.JFrame
import javax.swing.SwingUtilities

class Test: JFrame() {
    init {
        while (System.`in`.available() > 0) System.`in`.read()
        println("Do you want to quit Y/N")
        addKeyListener(object: KeyAdapter() {
            override fun keyPressed(e: KeyEvent) {
                if (e.keyCode == KeyEvent.VK_Y) {
                    println("OK, quitting")
                    quit()
                } else if (e.keyCode == KeyEvent.VK_N) {
                    println("N was pressed but the program is about to end anyway")
                    quit()
                } else {
                    println("Only Y/N are acceptable, please try again")
                }
            }
        })
    }

    private fun quit() {
        isVisible = false
        dispose()
        System.exit(0)
    }
}

fun main(args: Array<String>) {
    SwingUtilities.invokeLater {
        val f = Test()
        f.isFocusable = true
        f.isVisible = true
    }
}