public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

public class VariablesExample {
    public static void main(String[] args) {
        int age = 25;
        double salary = 3000.50;
        char grade = 'A';
        boolean isStudent = false;

        System.out.println("Age: " + age);
        System.out.println("Salary: " + salary);
        System.out.println("Grade: " + grade);
        System.out.println("Is student: " + isStudent);
    }
}

public class ArithmeticOperatorsExample {
    public static void main(String[] args) {
        int a = 10;
        int b = 3;

        int sum = a + b;
        int difference = a - b;
        int product = a * b;
        int quotient = a / b;
        int remainder = a % b;

        System.out.println("Sum: " + sum);
        System.out.println("Difference: " + difference);
        System.out.println("Product: " + product);
        System.out.println("Quotient: " + quotient);
        System.out.println("Remainder: " + remainder);
    }
}

Плохо: int a;
Хорошо: int age;

Пример: int userAge;

Пример: int userRegistrationYear;

Плохо: int usrAge;
Хорошо: int userAge;

Пример: final int MAX_USERS = 100;

Плохо: class A { }
Хорошо: class User { }

Пример: class UserProfile { }

Пример: class OrderProcessingService { }

Пример: interface IUser { }
Пример: interface Serializable { }

Плохо: void m() { }
Хорошо: void calculateSalary() { }

Пример: void sendEmail() { }

Пример: void updateUserProfile() { }

Пример: void generateMonthlyReport() { }

int a = 5;
int b = 5;
boolean result = (a == b); // true

int a = 5;
int b = 10;
boolean result = (a != b); // true

int a = 10;
int b = 5;
boolean result = (a > b); // true

int a = 5;
int b = 10;
boolean result = (a < b); // true

int a = 10;
int b = 10;
boolean result = (a >= b); // true

int a = 5;
int b = 10;
boolean result = (a <= b); // true

int age = 25;
boolean isAdult = age > 18;
boolean hasPermission = true;
boolean canEnter = isAdult && hasPermission; // true

boolean hasTicket = false;
boolean isVIP = true;
boolean canEnter = hasTicket || isVIP; // true

String str1 = new String("Hello");
String str2 = new String("Hello");
boolean result = str1.equals(str2); // true

class Person {
    String name;

    Person(String name) {
        this.name = name;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null || getClass() != obj.getClass()) return false;
        Person person = (Person) obj;
        return Objects.equals(name, person.name);
    }
}

Person person1 = new Person("Alice");
Person person2 = new Person("Alice");
boolean result = person1.equals(person2); // true

public class IfElseExample {
    public static void main(String[] args) {
        int number = 10;

        if (number > 0) { // условие первое
            System.out.println("The number is positive.");
        } else if (number < 0) { // дополнительное условие
            System.out.println("The number is negative.");
        } else { // блок "иначе", срабатывающий если условие в if равно false
            System.out.println("The number is zero.");
        }
    }
}

public class SwitchExample {
    public static void main(String[] args) {
        int dayOfWeek = 3;

        switch (dayOfWeek) {
            case 1:
                System.out.println("Monday");
                break;
            case 2:
                System.out.println("Tuesday");
                break;
            case 3:
                System.out.println("Wednesday");
                break;
            case 4:
                System.out.println("Thursday");
                break;
            case 5:
                System.out.println("Friday");
                break;
            case 6:
                System.out.println("Saturday");
                break;
            case 7:
                System.out.println("Sunday");
                break;
            default:
                System.out.println("Invalid day of the week.");
                break;
        }
    }
}

public class ForLoopExample {
    public static void main(String[] args) {
        for (int i = 1; i <= 5; i++) {
            System.out.println("Iteration: " + i);
        }
    }
}

public class WhileLoopExample {
    public static void main(String[] args) {
        int i = 1;

        while (i <= 5) {
            System.out.println("Iteration: " + i);
            i++;
        }
    }
}

public class DoWhileLoopExample {
    public static void main(String[] args) {
        int i = 1;

        do {
            System.out.println("Iteration: " + i);
            i++;
        } while (i <= 5);
    }
}

int[] numbers;

int numbers[];

numbers = new int[5]; // Массив для 5 элементов

int[] numbers = new int[5];

int[] numbers = {1, 2, 3, 4, 5};

double[] decimals = new double[10]; // Массив для хранения 10 дробных чисел
char[] characters = {'a', 'b', 'c'}; // Массив символов
String[] words = {"Hello", "world"}; // Массив строк

int firstNumber = numbers[0]; // Получение первого элемента массива
numbers[1] = 10; // Присвоение значения второму элементу массива

public class ArrayExample {
    public static void main(String[] args) {
        int[] numbers = {1, 2, 3, 4, 5};

        // Вывод всех элементов массива
        for (int i = 0; i < numbers.length; i++) {
            System.out.println("Element at index " + i + ": " + numbers[i]);
        }
    }
}

public class Main {
    public static void main(String[] args) {
        int x = 15;
        int y = 10;
        String result;

        if (x > y) {
            if (x % y == 0) {
                result = "A";
            } else {
                result = "B";
            }
        } else if (x < y) {
            result = "C";
        } else {
            result = "D";
        }

        System.out.println(result);
    }
}