Map 课堂练习

public class MapExercise {
    public static void main(String[] args) {
        /**
           使用 HashMap 添加 3个员工对象，要求：
           键：员工id
           值：员工对象
           遍历显示工资 > 18000 的员工 (最少用两种遍历方式)
           员工类：姓名、工资、员工id
        */
        Map map = new HashMap();

        map.put("01",new Emp("小米",14000,1));
        map.put("02",new Emp("华为",19000,2));
        map.put("03",new Emp("魅族",13000,3));
        map.put("04",new Emp("三星",20000,4));

        Set keyset = map.keySet();//先取出所有的Key，通过Key 取出对应的Value
        //增强for
        for (Object key : keyset) {
            //先获取value
            Emp emp = (Emp) map.get(key);
            if (emp.getSal()>18000)
            System.out.println(key+"——"+map.get(key));
        }
        System.out.println("——————————————————————————————————————");
        //迭代器
        Set entrySet = map.entrySet();
        Iterator iterator = entrySet.iterator();
        while (iterator.hasNext()) {
           Map.Entry entry = (Map.Entry) iterator.next();
           //通过entry取得 key 和 value
            Emp emp = (Emp) entry.getValue();
            if (emp.getSal()>18000)
                System.out.println(entry.getKey()+"——"+emp);
        }

    }
}
class Emp{
    private String name;
    private double sal;
    private int id;

    public Emp(String name, double sal, int id) {
        this.name = name;
        this.sal = sal;
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public double getSal() {
        return sal;
    }

    public void setSal(double sal) {
        this.sal = sal;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    @Override
    public String toString() {
        return "Emp{" +
                "name='" + name + '\'' +
                ", sal=" + sal +
                ", id=" + id +
                '}';
    }

}

输出：

02——Emp{name='华为', sal=19000.0, id=2}
04——Emp{name='三星', sal=20000.0, id=4}
——————————————————————————————————————
02——Emp{name='华为', sal=19000.0, id=2}
04——Emp{name='三星', sal=20000.0, id=4}