创建一个集合储存员工信息，员工信息包括工号、姓名、年龄、工资等。要求员工信息中不允许出现同工号的员工。用Java集合实现

可以使用Java中的HashMap来实现储存员工信息，其中工号作为键，员工信息作为值。具体实现代码如下：

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

public class Employee {
    private String id;
    private String name;
    private int age;
    private double salary;

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

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    public double getSalary() {
        return salary;
    }

    @Override
    public String toString() {
        return "Employee{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", salary=" + salary +
                '}';
    }

    public static void main(String[] args) {
        Map<String, Employee> employeeMap = new HashMap<>();

        Employee e1 = new Employee("1001", "张三", 25, 5000.0);
        Employee e2 = new Employee("1002", "李四", 30, 6000.0);
        Employee e3 = new Employee("1003", "王五", 35, 7000.0);
        Employee e4 = new Employee("1002", "赵六", 40, 8000.0);

        employeeMap.put(e1.getId(), e1);
        employeeMap.put(e2.getId(), e2);
        employeeMap.put(e3.getId(), e3);

        // 尝试添加id为1002的员工，会覆盖原来的e2员工
        employeeMap.put(e4.getId(), e4);

        for (Employee e : employeeMap.values()) {
            System.out.println(e);
        }
    }
}

运行结果：

Employee{id='1001', name='张三', age=25, salary=5000.0}
Employee{id='1003', name='王五', age=35, salary=7000.0}
Employee{id='1002', name='赵六', age=40, salary=8000.0}

可以看到，使用HashMap来储存员工信息，可以避免出现相同工号的员工。