Map课堂练习

Map接口和常用方法

使用HashMap添加3个员工对象,要求
键:员工id
值:员工对象
并遍历显示工资>18000的员工(遍历方式最少两种)
员工类:姓名、工资、员工id

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

@SuppressWarnings({"all"})
public class MapExercise {
    public static void main(String[] args) {
        //创建一个HashMap
        Map hashMap = new HashMap();

        //放入三个员工对象
        hashMap.put(1, new Employee("test1", 17000, 1));
        hashMap.put(2, new Employee("test2", 19000, 2));
        hashMap.put(3, new Employee("test3", 20000, 3));

        //1.使用keySet ->  增强for
        Set keySet = hashMap.keySet();
        for (Object key : keySet) {
            Employee employee = (Employee) hashMap.get(key);
            if (employee.getSalary() > 18000) {
                System.out.println(employee);
            }
        }

        //2.使用entrySet -> 迭代器
        Set entrySet = hashMap.entrySet();
        Iterator iterator = entrySet.iterator();
        while (iterator.hasNext()) {
            Map.Entry entry = (Map.Entry) iterator.next();

            //通过entry取得key和value
            Employee employee = (Employee) entry.getValue();
            if (employee.getSalary() > 18000) {
                System.out.println(employee);
            }
        }
    }
}

//创建员工对象
class Employee {
    private String name;//姓名
    private double salary;//工资
    private int eid;//员工id

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }

    public int getEid() {
        return eid;
    }

    public void setEid(int eid) {
        this.eid = eid;
    }

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