Java Exercise

anotes.md

Java Exercise

This are collection of java exercises. It was kinda fun ngl.

bus-reservation.java

package com.sample.bus.reservation;
import java.util.Scanner;
import java.util.Arrays;

/**
 *
 * @author lnfel
 */
public class BusReservation {
    /**
     * Display reserved seats
     * 
     * @linkplain https://stackoverflow.com/questions/15961130/align-printf-output-in-java
     * @param bus Matrix of bus seat rows
     * @return void
     */
    static void displayBusSeats(String[][] bus) {
        System.out.println("Bus seat reservation.");
        System.out.printf("%-9s", "");
        System.out.printf("%s", "Col 1 Col 2 Col 3 Col 4");
      
        for (int i = 0; i < bus.length; i++) {
            System.out.println("");
            int row = i + 1;
            System.out.printf("Row %-5s", row);
            for (String seat : bus[i]) {
                System.out.printf("%-6s", " " + seat);
            }
        }
        System.out.println("");
    }

    /**
     * Check if bus is fully booked
     * 
     * @param bus Matrix of bus seat rows
     */
    static boolean notFullyBooked(String[][] bus) {
        Long availableSeats = Arrays.stream(bus)
            .flatMap(Arrays::stream)
            .filter(value -> value.equals("*"))
            .count();
        
        return availableSeats > 0;
    }
    
    /**
     * Seat Coordinates object
     */
    static public class SeatCoordinates {
        public int row = 0;
        public int column = 0;
        public SeatCoordinates(int rowChosen, int columnChosen) {
            row = rowChosen -1;
            column = columnChosen -1;
        }
    }
    
    /**
     * Get input from user
     * User must provide a space separated integer to reserve a seat on the bus.
     * Example: 5 3
     * The above input reserves the bus seat 3 from row 5
     * 
     * If a user inputs a negative integer without a second input separated by space, the program will close.
     * 
     * @return Array of seatCoordinate input
     */
    static String[] getInput() {
        // Initialize scanner
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter row and seat number separated by space to reserve a seat on the bus: ");
        
        // Get input and split by space character
        String[] input = sc.nextLine().split(" ");
        
        // If input has is not separated by space, check if it is a negative number and terminate program
        if (input.length == 1 && Integer.parseInt(input[0]) < 0) {
            System.out.println("Exiting program, goodbye!");
            System.exit(0);
        }
        
        // Loop over asking for valid seatCoordinates until user provides one.
        while (input.length < 2) {
            System.out.println("To reserve a bus seat, please provide a seat row and column separated by space.");
            System.out.println("Example: to reserve seat 3 in row 5, enter 5 3");
            input = sc.nextLine().split(" ");
        }
        
        return input;
    }
    
    /**
     * Validate SeatCoordinate based on selected bus rows and columns
     * by referencing the bus matrix values.
     * 
     * @param seatCoordinates The selected seat coordinates to be reserved
     * @param bus The bus matrix that holds the seat plan
     * @return Returns whether SeatCoordinates are valid
     */
    static boolean validateSeatCoordinates(SeatCoordinates seatCoordinates, String[][] bus) {
        if (seatCoordinates.row > bus.length - 1) {
            System.out.println("Sorry the bus only has 10 rows, please select a row from 1 - 10.");
            return false;
        }
        
        if (seatCoordinates.column > bus[seatCoordinates.row].length - 1) {
            System.out.printf("Sorry, bus row %d has %d seats, please select a seat from 1 - %d. %n", seatCoordinates.row + 1, bus[seatCoordinates.row].length, bus[seatCoordinates.row].length);
            return false;
        }
        return true;
    }
    
    public static void main(String args[]) {
        String[][] bus = { 
          {"*", "*", "*", "*"},
          {"*", "*", "*", "*"},
          {"*", "*", "*", "*"},
          {"*", "*", "*", "*"},
          {"*", "*", "*", "*"},
          {"*", "*", "*", "*"},
          {"*", "*", "*", "*"},
          {"*", "*", "*", "*"},
          {"*", "*", "*", "*"},
          {"*", "*", "*", "*"},
        };
    
        displayBusSeats(bus);
        
        while (notFullyBooked(bus)) {
            System.out.println("");
            String[] input = getInput();
            SeatCoordinates seatCoordinates = new SeatCoordinates(Integer.parseInt(input[0]), Integer.parseInt(input[1]));
            System.out.printf("Reserved row %d column %d%n", seatCoordinates.row + 1, seatCoordinates.column + 1);
            boolean validSeatCoordinates = validateSeatCoordinates(seatCoordinates, bus);
            
            if (validSeatCoordinates) {
                bus[seatCoordinates.row][seatCoordinates.column] = "x";
                displayBusSeats(bus);
            } else {
                
            }
        }
        
        // Test while loop by automatically filling all seats until bus is full
        //while (notFullyBooked(bus)) {
        //    for (int i = 0; i < bus.length; i++) {
        //        for(int j = 0; j < bus[i].length; j++) {
        //            bus[i][j] = "x";
        //        }
        //        displayBusSeats(bus);
        //        System.out.println("");
        //    }
        //}
        
        if (!notFullyBooked(bus)) {
            System.out.println("Bus is full, departing shortly.");
        }
    }
}

wordle.java

import java.util.Random;
import java.util.Scanner;

/**
 *
 * @author lnfel
 */
public class wordle {
    /**
     * Display game stats
     * 
     * @param correctGuesses Array of booleans based on the length of the word to guess
     * @param lives Remaining tries to guess the word
     * @return void
     */
    static void displayCorrectGuesses(boolean[] correctGuesses, int lives) {
        System.out.print("Guessed characters: ");
        for (boolean guessed: correctGuesses) {
            
            System.out.printf("%-2s", guessed ? "✓" : "x");
        }
        System.out.printf("Lives left: %-2d", lives);
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        String[] words = {"apple", "banana", "cherry", "orange", "pear"};
        Random random = new Random();
        int index = random.nextInt(words.length);
        String wordToGuess = words[index];
        int currentLetter = 0;
        boolean[] correctGuesses = new boolean[wordToGuess.length()];
        int lives = 8;
        Scanner scanner = new Scanner(System.in);

        while (lives > 0) {
            displayCorrectGuesses(correctGuesses, lives);
            System.out.print("Guess a letter: ");
            String guess = scanner.nextLine();
            boolean foundLetter = wordToGuess.charAt(currentLetter) == guess.charAt(0);
            
            if (foundLetter) {
                correctGuesses[currentLetter] = true;
                currentLetter++;
            } else {
                lives--;
            }
            
            if (currentLetter == wordToGuess.length()) {
                break;
            }
            
            if (lives == 0) {
                System.out.println("Game Over");
            }
        }
        
        if (lives > 0) {
            System.out.println("You win!");
        }
    }
}