auctionbid.java

java 完全探索的随书源码

import java.util.*;
import java.text.NumberFormat;
public class AuctionBid implements Comparable {

  // class holds the bidder's name and the amount bid
  String bidder;
  int amount;

  public AuctionBid(String name, int bid) {
    bidder = name;
    amount = bid;
  }

  public String toString() {
    // get a currency formatter to make the output look nice
    NumberFormat formatter = NumberFormat.getCurrencyInstance();
    return bidder + " bid " + formatter.format(amount);
  }

  // implement Comparable interface
  public int compareTo( Object other ) {
    // this method defines the natural ordering of
    // the class to be based on ascending bid amount
    AuctionBid otherBid = (AuctionBid)other;
    if ( otherBid == null ) {
      return 1;
    }
    if ( this.equals(otherBid) || (amount == otherBid.amount) ) {
      return 0;
    }
    return ( otherBid.amount < amount ) ? 1 : -1;
  }

  // define a Comparator that instead sorts on the bidder's name
  static class BidComparator implements Comparator, java.io.Serializable {
    public int compare(Object o1, Object o2) {
      AuctionBid firstBid = (AuctionBid)o1;
      AuctionBid secondBid = (AuctionBid)o2;
      if ( (firstBid == null) || (firstBid.bidder == null) ) {
        return ((secondBid == null) || (secondBid.bidder == null)) ? 0 : -1;
      }
      if ( (secondBid == null) || (secondBid.bidder == null) ) {
        return 1;
      }
      // String implements Comparable, so let it do the work
      return firstBid.bidder.compareTo(secondBid.bidder);
    }
  }

  public static void main( String args[] ) {
    // fill a list with 5 bids
    ArrayList bidList = new ArrayList();
    for ( int i=0; i<5; i++ ) {
      // generate a random number 0-100 for a bid amount
      bidList.add( new AuctionBid("Bidder" + i, (int)(Math.random()*100)) );
    }

    // sort the bids in natural order and display them
    Collections.sort( bidList );
    System.out.println("Natural order sort by bid amount");
    System.out.println( bidList );

    // impose a different sort using a Comparator
    Collections.sort( bidList, new BidComparator() );
    System.out.println("Comparator sort by bidder name");
    System.out.println( bidList );
  }
}