黑马软件工程师——java——Map集合的子类HashMap的简单操作方法

黑马程序员——java——Map集合的子类HashMap的简单操作方法

Map集合的子类HashMap的简单操作方法

import java.util.HashMap;
import java.util.Iterator;


public class HashMapDemos 
{
	public static void%r0main(String[] args) 
	{
		// 
		HashMap<Studenti,String> hm = new HashMap<Studenti,String>();
		hm.put(new Studenti("kk",22), "山西");
		hm.put(new Studenti("jj",20), "山东");
		hm.put(new Studenti("hh",25), "上海");

		Iterator<Studenti> it = hm.keySet().iterator();
		while(it.hasNext())
		{
			Studenti key = it.next();
			String value = hm.get(key);
			System.out.println(key.toString()+"  --"+value);
		}
	}

}

class Studenti
{
	private String name;
	private int age;
	Studenti(String name ,int age)
	{
		this.name=name;
		this.age = age;
	}
	public int getAge()
	{
		return age;
		
	}
	public String getName()
	{
		return name;
		
	}
	public String toString()
	{
		return "the student name :" +name +"  and  age is : "+ age;
		
	}
	public int hashCode()
	{
		return name.hashCode()+age*10;
		
	}
	public boolean equals(Object obj)
	{
		 if(this == obj)
             return true ;//同一个对象放两次，直接返回true
      
       if(!(obj instanceof Studenti))
             throw new ClassCastException("类型错误");

       Studenti p = (Studenti)obj;

       return this .name.equals(p.name) && this.age == p.age;
	}
	}

运行程序：