尚硅谷-集合笔记4

package com.java1;

import org.junit.Test;

import java.util.HashSet;
import java.util.Iterator;
import java.util.linkedHashSet;
import java.util.Set;


public class SetTest {
    
    @Test
    public void test1(){
        Set set=new HashSet();
        set.add(456);
        set.add(123);
        set.add(123);
        set.add("AA");
        set.add("CC");
        set.add(new User("Tom",12));
        set.add(new User("Tom",12));
        set.add(129);

        //System.out.println(set);//[AA, CC, 129, 456, 123, Person{name='Tom', age=12}]
        Iterator iterator = set.iterator();
        while (iterator.hasNext()){
            System.out.println(iterator.next());// AA CC 129 456 123
        }

    }

    //linkedHashSet的使用：
    //linkedHashSet作为HashSet的子类，在添加数据的同时，每个数据还维护了两个引用，记录此数据前一个和后一个数据。以链表形式进行。
    //优点：对于频繁的遍历操作，linkedHashSet高于HashSet
    @Test
    public void test2(){
        Set set=new linkedHashSet();
        set.add(456);
        set.add(123);
        set.add(123);
        set.add("AA");
        set.add("CC");
        set.add(new User("Tom",12));
        set.add(new User("Tom",12));
        set.add(129);

        //System.out.println(set);//[AA, CC, 129, 456, 123, Person{name='Tom', age=12}]
        Iterator iterator = set.iterator();
        while (iterator.hasNext()){
            System.out.println(iterator.next());// AA CC 129 456 123
        }

    }
}

package com.java1;

import org.junit.Test;

import java.util.Comparator;
import java.util.Iterator;
import java.util.TreeSet;


public class TreeSetTest {
    
    @Test
    public void test1() {
        TreeSet set = new TreeSet();

        //不能添加不同类的对象；因为TreeSet主要作用就是用来排序，对象都不能无法排序
//        set.add(123);
//        set.add(456);
//        set.add("AA");
//        set.add(new User("Tom",12));
        //举例一：
//        set.add(34);
//        set.add(-34);
//        set.add(43);
//        set.add(11);
//        set.add(8);
//        Iterator iterator = set.iterator();
//
//        while (iterator.hasNext()){
//            System.out.println(iterator.next());//-34 8 11 34 43 按照从小到大的顺序进行排
//        }

        //举例二：
        set.add(new User("Tom",12));
        set.add(new User("Jerry",32));
        set.add(new User("Jim",2));
        set.add(new User("Mike",65));
        set.add(new User("Jack",33));
        set.add(new User("Jack",56));

        Iterator iterator = set.iterator();

        while (iterator.hasNext()){
            System.out.println(iterator.next());//
        }
    }

    @Test
    public void test2(){
        Comparator com=new Comparator() {
            //按照年龄从小到大排列
            @Override
            public int compare(Object o1, Object o2) {
                if(o1 instanceof User && o2 instanceof User){
                    User u1=(User)o1;
                    User u2=(User)o2;
                    return Integer.compare(u1.getAge(),u2.getAge());
                }else{
                    throw new RuntimeException("输入的数据类型不匹配");
                }
            }
        };
        TreeSet set=new TreeSet(com);
        set.add(new User("Tom",12));
        set.add(new User("Jerry",32));
        set.add(new User("Jim",2));
        set.add(new User("Mike",65));
        set.add(new User("Jack",33));
        set.add(new User("Mary",33));
        set.add(new User("Jack",56));

        Iterator iterator = set.iterator();

        while (iterator.hasNext()){
            System.out.println(iterator.next());//
        }
    }



















}

package com.java1;


public class User implements Comparable{
    private String name;
    private  int age;

    public User() {
    }

    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

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

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + ''' +
                ", age=" + age +
                '}';
    }

    @Override
    public boolean equals(Object o) {
        System.out.println("User equals");
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        User user = (User) o;

        if (age != user.age) return false;
        return name != null ? name.equals(user.name) : user.name == null;
    }

    @Override
    public int hashCode() {//return name.hashCode()+age;自己写的也可比较low
        int result = name != null ? name.hashCode() : 0;
        result = 31 * result + age;
        return result;
    }

    //按照姓名从大到小排列，年龄从小到大排列
    @Override
    public int compareTo(Object o) {
        if(o instanceof User){
            User user=(User)o;
//            return this.name.compareTo(user.name);
            int compare =-this.name.compareTo(user.name);
            if(compare !=0){
                return compare;
            }else{
                return Integer.compare(this.age,user.age);
            }
        }else{
            throw new RuntimeException("输入类型不匹配");
        }
    }
}