Java基础之一组有用的类——使用二叉树搜索算法搜索某个作者（TryBinarySearch）

控制台程序。

Arrays类中的binarySearch()静态方法使用二叉树搜索算法，在有序数组中查找包含给定值的元素。只有当数组的元素按升序方式排序时，该方法才是最有效的，否则就应在调用binarySearch()方法之前调用sort()方法。

binarySearch()方法的所有版本都返回int类型的值，也就是在array中找到value的索引位置。当然，value也可能不在数组中，此时返回一个负整数。计算过程是：提取大于value的第一个元素的索引位置，翻转元素的取值符号后再减1.

 public class Person implements Comparable<Person> {
   // Constructor
   public Person(String firstName, String surname) {
     this.firstName = firstName;
     this.surname = surname;
   }

   @Override
   public String toString() {
     return firstName + " " + surname;
   }

   // Compare Person objects
   public int compareTo(Person person) {
     int result = surname.compareTo(person.surname);
     return result == 0 ? firstName.compareTo(person.firstName) : result;
   }

   public String getFirstName() {
     return firstName;
   }

   public String getSurname() {
     return surname;
   }
   private String firstName;                                            // First name of person
   private String surname;                                              // Second name of person
 }

 import java.util.Arrays;

 public class TryBinarySearch {
   public static void main(String[] args) {
     Person[] authors = {
             new Person("Danielle", "Steel"), new Person("John", "Grisham"),
             new Person("Tom", "Clancy"),     new Person("Christina", "Schwartz"),
             new Person("Patricia", "Cornwell"), new Person("Bill", "Bryson")
                        };

     Arrays.sort(authors);                                              // Sort using Comparable method

     System.out.println("\nOrder after sorting into ascending sequence:");
     for(Person author : authors) {
       System.out.println(author);
     }

     // Search for authors
     Person[] people = {
          new Person("Christina", "Schwartz"),    new Person("Ned", "Kelly"),
          new Person("Tom", "Clancy"),        new Person("Charles", "Dickens")
                       };
      int index = 0;
     System.out.println("\nIn search of authors:");
     for(Person person : people) {
       index = Arrays.binarySearch(authors, person);
       if(index >= 0) {
         System.out.println(person + " was found at index position " + index);
       } else {
         System.out.println(person + " was not found. Return value is " + index);
       }
     }
   }
 }