Java SortedSet TreeSet按指定方式排序 不同方式排序

//实现Things类
class Things{
	public String name;
	public String id;
	String location;
	public String arrivetime;
	

	Things(String id, String name,String location,String arrivetime){
		this.id=id;
		this.name=name;
		this.location=location;
		this.arrivetime=arrivetime;
	}

	public String toString(){
		return"id:"+id+"\tname:"+name+"\tlocation:"+location+"\tarrivetime:"+arrivetime+"\n";
	}

}

//实现按ID进行比较
import java.util.Comparator;
public class SortById implements Comparator<Object>{

	@Override
	public int compare(Object o1, Object o2) {
		Things th1=(Things)o1;
		Things th2=(Things)o2;
		return th1.id.compareTo(th2.id);
	}
}

//实现按Time进行比较
import java.util.Comparator;
public class SortByTime implements Comparator<Object>{

	@Override
	public int compare(Object o1, Object o2) {
		Things th1=(Things)o1;
		Things th2=(Things)o2;
		return th1.arrivetime.compareTo(th2.arrivetime);
	}
}

//测试
import java.util.*;
class Demo5{
	public static void main(String args[]) {

	SortedSet<Things> ssa=new TreeSet<Things>(new SortById());	//创建一个按照Id排序的TreeSet实例a
	SortedSet<Things> ssb=new TreeSet<Things>(new SortByTime());	//创建一个按照Time排序的TreeSet实例b

	ssa.add(new Things("001","A","库1","2001-01-10"));	//添加的时候时间必须标准比如2011-11-1必须写成2011-11-01
	ssa.add(new Things("002","A","库1","2011-10-31"));
	ssa.add(new Things("003","B","库1","2011-10-03"));
	ssa.add(new Things("006","A","库2","2011-10-01"));
	ssa.add(new Things("007","B","库2","2011-10-30"));
	ssa.add(new Things("008","B","库2","2011-09-12"));
	ssa.add(new Things("004","B","库1","2011-09-02"));
	ssa.add(new Things("005","A","库2","2001-01-09"));

	
	int count1=0,count2=0,count3=0,count4=0;
	System.out.println("按ID排序:");
	Iterator<Things> it = ssa.iterator();
	while(it.hasNext()){
		Things c = it.next();
		ssb.add(c);	//从a中不断读取的时候就在b中添加
		System.out.print(c);
		if(c.name=="A" && c.location=="库1")
			 count1++;
			else 
			if(c.name=="A" && c.location=="库2")
			 count2++;	
			else
			if(c.name=="B" && c.location=="库1")
			 count3++;
			else
			if(c.name=="B" && c.location=="库2")
			 count4++;
	}
	
	
	System.out.println("按时间排序:");
	it = ssb.iterator();
	while(it.hasNext()){
		Things c = it.next();
		System.out.print(c);
	}

	System.out.println("A物料在库1的库存量为："+count1);
	System.out.println("A物料在库2的库存量为："+count2);
	System.out.println("B物料在库1的库存量为："+count3);
	System.out.println("B物料在库2的库存量为："+count4);
	}
}