黑马程序17-8：HashMap与TreeMap区别及ComparatorByName比较器的用法，IDE快捷生成hashCode()与equals()比较代码

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package cn.itcast.p2.bean;

public class Person implements Comparable<Person> {

	private String name;
	private int age;

	public Person() {
		super();
		
	}

	public Person(String name, int age) {
		super();
		this.name = name;
		this.age = age;
	}
	public int compareTo(Person p){
		
//		Person p = (Person)obj;
		int temp = this.age - p.age;
		return temp==0?this.name.compareTo(p.name):temp;
	}
	
	//！！！！用IDE快捷生成，重写hashCode对应本类属性的判断唯一性，将重复的对象去掉
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + age;
		result = prime * result + ((name == null) ? 0 : name.hashCode());
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Person other = (Person) 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;
	}

	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}

	@Override
	public String toString() {
		
		return "Person:"+getName()+":"+getAge();
	}
}

package cn.itcast.p8.treemap.demo;

import java.util.Iterator;
import java.util.Map;
import java.util.TreeMap;

import cn.itcast.p2.bean.Student;
import cn.itcast.p3.comparator.ComparatorByName;

public class TreeMapDemo {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		//TreeMap有个比较器，而Student是Person的子类，所以newComparatorByName一样用
		TreeMap<Student,String> tm = new TreeMap<Student,String>(new ComparatorByName());
		
		tm.put(new Student("lisi",38),"北京");
		tm.put(new Student("zhaoliu",24),"上海");
		tm.put(new Student("xiaoqiang",31),"沈阳");
		tm.put(new Student("wangcai",28),"大连");
		tm.put(new Student("zhaoliu",24),"铁岭");

		Iterator<Map.Entry<Student, String>> it = tm.entrySet().iterator();
		while(it.hasNext()){
			Map.Entry<Student,String> me = it.next();
			Student key = me.getKey();
			String value = me.getValue();
			
			System.out.println(key.getName()+":"+key.getAge()+"---"+value);
		}
		
	}

}

package cn.itcast.p7.hashmap.demo;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
import cn.itcast.p2.bean.Student;

public class HashMapDemo {

	/**
	 * @param args
	 */
	public static void main(String[] args) {

		/*
		 * 将学生对象和学生的归属地通过键与值存储到map集合中。
		 * 
		 */
		//！！！HashMap是无序的，TreeMap是有序的！！！
		HashMap<Student,String> hm = new HashMap<Student,String>();
	
		hm.put(new Student("lisi",38),"北京");
		hm.put(new Student("zhaoliu",24),"上海");
		hm.put(new Student("xiaoqiang",31),"沈阳");
		hm.put(new Student("wangcai",28),"大连");
		hm.put(new Student("zhaoliu",24),"铁岭");
		
//		Set<Student> keySet = hm.keySet();		
//		Iterator<Student> it = keySet.iterator();
		Iterator<Student> it = hm.keySet().iterator();
		
		while(it.hasNext()){
			Student key = it.next();
			String value = hm.get(key);
			System.out.println(key.getName()+":"+key.getAge()+"---"+value);
		}
	}
}

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