binarydemo.java

Java学习源代码检索系统免费版

//==============================================================
// BinaryDemo.java - Search a container using Collections.binarySearch()
//
// Java学习源代码检索系统 Ver 1.0 20031015 免费正式版
// 版权所有: 中国IT认证实验室(www.ChinaITLab.com)
// 程序制作: ChinaITLab网校教研中心
// 主页地址: www.ChinaITLab.com    中国IT认证实验室
// 论坛地址: bbs.chinaitlab.com  
// 电子邮件: [e-mail]
//==============================================================

import java.util.List;
import java.util.Comparator;
import java.util.ArrayList;
import java.util.Collections;
import Chart;

class BinaryDemo {

 // Display a List container's contents
 public static void showContainer(List c) {
  for (int i = 0; i < c.size(); i++)
   System.out.println(c.get(i).toString());
 }

 public static void main(String args[]) {
// Construct the container
  ArrayList charts = new ArrayList();

// Insert some Data objects
  charts.add(new Chart(11013, "Morehead City Hrbr ", 12500));
  charts.add(new Chart(11552, "Neuse River        ", 40000));
  charts.add(new Chart(11428, "Dry Tortugas       ", 30000));
  charts.add(new Chart(11420, "Havana to Tampa Bay", 470940));
  charts.add(new Chart(25641, "Virgin Islands     ", 100000));
  charts.add(new Chart(26341, "Bermuda Islands    ", 50000));

// Display all objects if none requested
  if (args.length == 0) {
   System.out.println("\nContainer contents:");
   showContainer(charts);
   System.out.println("\nEnter a chart number to find");
   System.out.println("ex. java BinaryDemo 11428");
  } else {

// Search container using Collections.binarySearch()
   try {
// Preparations for a binarySearch();
    int num = Integer.parseInt(args[0]); // Get chart number
    Comparator comp = Chart.byNumber();  // Create Comparator
    Chart key = new Chart(num, "", 0);   // Create search key 
    Collections.sort(charts, comp);      // Sort container

// Search the container for the key object
    int index = Collections.binarySearch(charts, key, comp);
    if (index < 0)
     System.out.println("Chart #" + args[0] + " not found");
    else
     System.out.println(charts.get(index)); // Show chart
   }
    catch (NumberFormatException e) {
    System.out.println("Error in argument " + e.getMessage());
   }
  }
 }
}