java- 比較排序與hash

java- 比較排序與hash

package dplearn;

import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;



public class Learn {
	public static void main(String[] args){
		Basicinfo[] myBs=new Basicinfo[3];
		myBs[0]=new Basicinfo("虎頭牌筆記本",8.5f,"red");
		myBs[1]=new Basicinfo("A4紙",25.8f,"white");
	    myBs[2]=new Basicinfo("B2鉛筆",1.2f,"black");
	    Arrays.sort(myBs);
        for (Basicinfo bsinfo:myBs){
        	System.out.println(bsinfo.info());
        }
        System.out.println("------");
	    Arrays.sort(myBs,Collections.reverseOrder());
        for (Basicinfo bsinfo:myBs){
        	System.out.println(bsinfo.info());
        }
        Map mymap=new HashMap();
        mymap.put(1, "abc");
        mymap.put(2, "123");        
        mymap.put(3, "823");
        mymap.put(2, "qqq");//修改鍵值
        System.out.println("------");
        Set keys = mymap.keySet();
        for (Object key:keys){
        	System.out.println(keys+"=>"+mymap.get(key));
        }
	}
}

package dplearn; public class Basicinfo implements Comparable{ String name; float price; String color; public Basicinfo(){ name=""; price=0; color=""; } public Basicinfo(String name,float price,String color){ this.name=name; this.price=price; this.color=color; } public String info(){ return "name:"+this.name+"=>price:"+this.price+"=>color:"+this.color; } @Override public int compareTo(Object obj) { // TODO Auto-generated method stub Basicinfo anotherBsinfo=(Basicinfo)obj; if (anotherBsinfo.price > this.price) { return 1; } else if (anotherBsinfo.price < this.price) { return -1; } else{ return 0; } } } 

name:A4紙=>price:25.8=>color:white

name:虎頭牌筆記本=>price:8.5=>color:red

name:B2鉛筆=>price:1.2=>color:black

------

name:B2鉛筆=>price:1.2=>color:black

name:虎頭牌筆記本=>price:8.5=>color:red

name:A4紙=>price:25.8=>color:white

------

[1, 2,3]=>abc

[1, 2,3]=>qqq

[1, 2,3]=>823