類對象數組以及排序問題

package java作業;

import java.util.Arrays;

 class BankAccount implements Comparable{ //實現了Comparable接口後可以調用Arrays.sort方法
  double money;
  String BankNum;
  BankAccount(double money,String BankNum){
   this.money=money;
   this.BankNum=BankNum;
  }
 public int compareTo(Object o) { //Comparable中定義的方法
  BankAccount a=(BankAccount) o;

/* 按升序排列*/
  if(money<a.money)
   return -1;
  else if (money>a.money)
   return 1;
  else
  return 0;
 }

/*降序排列

if(money<a.money)
   return 1;
  else if (money>a.money)
   return -1;
  else
  return 0;
 */
}
public class TestBankAccount {

 public static void main(String[] args) {
  // TODO 自動生成的方法存根
  BankAccount []list=new BankAccount[3];
  list[0]=new BankAccount(2000,"123456");
  list[1]=new BankAccount(1000,"123457");
  list[2]=new BankAccount(3000,"123459");
  Arrays.sort(list);
  int i=0;
  for(i=0;i<list.length;i++){
   System.out.println("money:"+list[i].money+",BankNum:"+list[i].BankNum);
  }
 }
}

輸出結果：money:1000.0,BankNum:123457
money:2000.0,BankNum:123456
money:3000.0,BankNum:123459