chapter9n4.java

JAVA源代码程序aashjkjhkjhkjhjkhkj

/**
 *
 * searching a sorted array
 *
 * Written by: Roger Garside
 *
 * First Written: 11/Oct/96
 * Last Rewritten: 13/Oct/96
 *
 */

import java.lancs.* ;

public class Chapter9n4
    {

    /**
     *
     * main
     *
     */

    public static void main(String[] args) throws Exception
        {
	BasicIo.prompt("type file name: ") ;
        String fileName = BasicIo.readString() ;

	// read the data in
        Person[] personGroup = new Person[100] ;
        BasicFileIo file = new BasicFileIo(BasicFileIo.INPUT, fileName) ;
        int noOfPersons = 0 ;
        while (true)
	    {
	    String fore = file.readString() ;
	    if (fore == null)
	        break ;
            String sur = file.readString() ;
	    int age = file.readInteger() ;
	    String x = file.readString() ;
	    int gender ;
	    if (x.equalsIgnoreCase("MALE"))
	        gender = Person.MALE ;
	    else if (x.equalsIgnoreCase("FEMALE"))
	        gender = Person.FEMALE ;
	    else
	        gender = Person.UNKNOWN ;
            personGroup[noOfPersons] = new Person(fore, sur, age, gender) ;
	    noOfPersons++ ;
	    }
        file.closeFile() ;

	// display the (unsorted) data
        for (int i = 0 ; i < noOfPersons ; i++)
    	    System.out.println(i + ": " +
		personGroup[i].getForename() + " " +
		personGroup[i].getSurname() + " " +
		personGroup[i].getAge()) ;

	// sort the data
        for (int i = 1 ; i < noOfPersons ; i++)
	    {
	    int j = i ;
	    String s = personGroup[i].getSurname() ;
	    Person p = personGroup[i] ;
	    while ((j > 0) &&
                   (personGroup[j - 1].getSurname().compareTo(s) > 0))
	        {
	        personGroup[j] = personGroup[j - 1] ;
	        j-- ;
	        }
            personGroup[j] = p ;
	    }
        System.out.println() ;

	// display the sorted data
        for (int i = 0 ; i < noOfPersons ; i++)
	    System.out.println(i + ": " +
		   personGroup[i].getForename() + " " +
		   personGroup[i].getSurname() + " " +
		   personGroup[i].getAge()) ;

	// search for a specified surname
        BasicIo.prompt("Type the surname to be searched for: ") ;
        String surname = BasicIo.readString() ;
	// linear search
        /* int i = 0 ;
        boolean matchSurname = false ;
        while (i < noOfPersons)
	    {
	    int result = personGroup[i].getSurname().compareTo(surname) ;
	    if (result == 0)
	        {
	        matchSurname = true ;
	        break ;
	        }
            else if (result > 0)
	        break ;
            i++ ;
            }
        if (matchSurname)
	    System.out.println("found at position " + i) ;
        else
	    System.out.println("no such person") ; */
	// binary search
        int i = -1 ;
        int j = noOfPersons ;
        int k = 0 ;
        boolean matchSurname = false ;
        while (((i + 1) < j) && (!matchSurname))
	    {
	    k = (i + j) / 2 ;
	    int result = personGroup[k].getSurname().compareTo(surname) ;
	    if (result == 0)
	        matchSurname = true ;
	    else if (result < 0)
	        i = k ;
	    else // i.e. result > 0
	        j = k ;
            }
        if (matchSurname)
	    System.out.println("found at position " + k) ;
        else
	    System.out.println("no such person") ;
        } // end of method main

    } // end of class Chapter9n4