list、set、map集合的综合应用

 定义一个Worker类,属    性:name:String,age:int,salary:double 
a).把若干Worker对象放在List中,排序并遍历输出
两种方式      1）利用comparable 接口--》按年龄升序排列
                    2）利用comparator接口--》按工资降序排列
b).把若干Worker对象放在Set中并遍历,要求没有重复元素，内容相同标准（名字和年龄相同）

c).把若干Worker对象放在Map中，并按照两种方式分别遍历键和值,要求以Worker的姓名作为key，worker对象作为value。

import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.HashMap;import java.util.HashSet;import java.util.Iterator;/** 2  定义一个Worker类,属    性:name:String,age:int,salary:double a).把若干Worker对象放在List中,排序并遍历输出两种方式      1）利用comparable 接口--》按年龄升序排列                    2）利用comparator接口--》按工资降序排列b).把若干Worker对象放在Set中并遍历,要求没有重复元素，内容相同标准（名字和年龄相同）c).把若干Worker对象放在Map中，并按照两种方式分别遍历键和值,要求以Worker的姓名作为key，worker对象作为value。 *  * */import java.util.List;import java.util.Map;import java.util.Map.Entry;import java.util.Set;public class Test4 {public static void main(String[] args) {demo1();demo2();demo3();}public static void demo1(){List<Worker> list=new ArrayList<Worker>();Worker worker1=new Worker("张三",18,5000);Worker worker2=new Worker("张三1",19,2000);Worker worker3=new Worker("张三2",17,3000);Worker worker4=new Worker("张三3",20,4000);list.add(worker1);list.add(worker2);list.add(worker3);list.add(worker4);System.out.println("排序前：");System.out.println(list);Collections.sort(list);System.out.println("按年龄升序输出：");System.out.println(list);Collections.sort(list,new WorkerComparator());System.out.println("按工资降序输出：");System.out.println(list);}public static void demo2(){Set<Worker> set=new HashSet<Worker>();Worker worker1=new Worker("张三",18,5000);Worker worker2=new Worker("张三1",19,2000);Worker worker3=new Worker("张三2",17,3000);Worker worker4=new Worker("张三3",20,4000);Worker worker5=new Worker("张三",18,5000);set.add(worker1);set.add(worker2);set.add(worker3);set.add(worker4);set.add(worker5);System.out.println("set遍历:");for(Worker temp:set){System.out.println(temp);}}public static void demo3(){Map<String,String> map=new HashMap<String,String>();map.put("张三", "18,5000");map.put("张三1", "16,4000");map.put("张三2", "14,1000");map.put("张三3", "19,6000");System.out.println("map遍历一：");Set<String> keySet=map.keySet();for(String key:keySet){System.out.println("名字："+key+" 年龄和工资："+map.get(key));}System.out.println("map遍历二：");Set<Entry<String,String>> ss=map.entrySet();for(Iterator iterator=ss.iterator();iterator.hasNext();){Entry e=(Entry) iterator.next();System.out.println("名字："+e.getKey()+" 年龄和工资："+e.getValue());}}}class WorkerComparator implements Comparator{public int compare(Object o1,Object o2){if(o1 instanceof Worker && o2 instanceof Worker){Worker p1=(Worker)o1;Worker p2=(Worker)o2;if(p1.salary>p2.salary){return -1;}if(p1.salary<p2.salary){return 1;}return 0;}return 0;}}class Worker implements Comparable<Worker>{String name;int age;double salary;public Worker(String name, int age, double salary) {super();this.name = name;this.age = age;this.salary = salary;}@Overridepublic String toString() {return "\nWorker [name=" + name + ", age=" + age + ", salary=" + salary + "]";}public int compareTo(Worker o){if(this.age>o.age){return 1;}else if(this.age<o.age){return -1;}else{return 0;}}@Overridepublic int hashCode() {final int prime = 31;int result = 1;result = prime * result + age;result = prime * result + ((name == null) ? 0 : name.hashCode());return result;}@Overridepublic boolean equals(Object obj) {if (this == obj)return true;if (obj == null)return false;if (getClass() != obj.getClass())return false;Worker other = (Worker) obj;if (age != other.age)return false;if (name == null) {if (other.name != null)return false;} else if (!name.equals(other.name))return false;return true;}}