用java生成存储多个员工信息包括工号、姓名、年龄入职时间打印所有员工姓名并输出 员工的 个数。使用四种方式

1. 使用数组

public class Employee {
    private int id;
    private String name;
    private int age;
    private LocalDate hireDate;

    public Employee(int id, String name, int age, LocalDate hireDate) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.hireDate = hireDate;
    }

    public String getName() {
        return name;
    }
}

public class Main {
    public static void main(String[] args) {
        Employee[] employees = new Employee[3];
        employees[0] = new Employee(1, "John", 25, LocalDate.of(2020, 1, 1));
        employees[1] = new Employee(2, "Mary", 30, LocalDate.of(2015, 1, 1));
        employees[2] = new Employee(3, "Tom", 35, LocalDate.of(2010, 1, 1));

        int count = employees.length;
        System.out.println("Total employees: " + count);

        for (Employee employee : employees) {
            System.out.println(employee.getName());
        }
    }
}

2. 使用列表

import java.util.ArrayList;
import java.util.List;

public class Employee {
    private int id;
    private String name;
    private int age;
    private LocalDate hireDate;

    public Employee(int id, String name, int age, LocalDate hireDate) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.hireDate = hireDate;
    }

    public String getName() {
        return name;
    }
}

public class Main {
    public static void main(String[] args) {
        List<Employee> employees = new ArrayList<>();
        employees.add(new Employee(1, "John", 25, LocalDate.of(2020, 1, 1)));
        employees.add(new Employee(2, "Mary", 30, LocalDate.of(2015, 1, 1)));
        employees.add(new Employee(3, "Tom", 35, LocalDate.of(2010, 1, 1)));

        int count = employees.size();
        System.out.println("Total employees: " + count);

        for (Employee employee : employees) {
            System.out.println(employee.getName());
        }
    }
}

3. 使用Map

import java.util.HashMap;
import java.util.Map;

public class Employee {
    private int id;
    private String name;
    private int age;
    private LocalDate hireDate;

    public Employee(int id, String name, int age, LocalDate hireDate) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.hireDate = hireDate;
    }

    public String getName() {
        return name;
    }
}

public class Main {
    public static void main(String[] args) {
        Map<Integer, Employee> employees = new HashMap<>();
        employees.put(1, new Employee(1, "John", 25, LocalDate.of(2020, 1, 1)));
        employees.put(2, new Employee(2, "Mary", 30, LocalDate.of(2015, 1, 1)));
        employees.put(3, new Employee(3, "Tom", 35, LocalDate.of(2010, 1, 1)));

        int count = employees.size();
        System.out.println("Total employees: " + count);

        for (Employee employee : employees.values()) {
            System.out.println(employee.getName());
        }
    }
}

4. 使用Set

import java.util.HashSet;
import java.util.Set;

public class Employee {
    private int id;
    private String name;
    private int age;
    private LocalDate hireDate;

    public Employee(int id, String name, int age, LocalDate hireDate) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.hireDate = hireDate;
    }

    public String getName() {
        return name;
    }
}

public class Main {
    public static void main(String[] args) {
        Set<Employee> employees = new HashSet<>();
        employees.add(new Employee(1, "John", 25, LocalDate.of(2020, 1, 1)));
        employees.add(new Employee(2, "Mary", 30, LocalDate.of(2015, 1, 1)));
        employees.add(new Employee(3, "Tom", 35, LocalDate.of(2010, 1, 1)));

        int count = employees.size();
        System.out.println("Total employees: " + count);

        for (Employee employee : employees) {
            System.out.println(employee.getName());
        }
    }
}
``