chapter9n5.java

JAVA源代码程序aashjkjhkjhkjhjkhkj

/**
 *
 * searching a sorted array (2)
 *
 * Written by: Roger Garside
 *
 * First Written: 11/Oct/96
 * Last Rewritten: 13/Oct/96
 *
 */

import java.io.* ;
import java.lancs.* ;

public class Chapter9n5
    {

    /**
     *
     * main
     *
     */

    public static void main(String[] args) throws Exception
        {
	int MAX_NO_OF_PERSONS = 100 ;
        Person[] personGroup = new Person[MAX_NO_OF_PERSONS] ;
        int noOfPersons = 0 ;
	
	// read the data in
	BasicIo.prompt("type file name: ") ;
        String fileName = BasicIo.readString() ;
	noOfPersons = readArray(fileName, personGroup) ;
	System.out.println("read " + noOfPersons + " elements from file "
				 + fileName) ;

	// display the (unsorted) data
	displayArray(personGroup, noOfPersons) ;

	// sort the array
	sortArray(personGroup, noOfPersons) ;

	// display the sorted data
	System.out.println() ;
	displayArray(personGroup, noOfPersons) ;

	// search for a specified surname
	searchArray(personGroup, noOfPersons) ;
        } // end of main method

    /**
     *
     * readArray
     *
     */

    private static int readArray(String name, Person[] array)
			throws IOException
	{
        BasicFileIo file = new BasicFileIo(BasicFileIo.INPUT, name) ;
	int arrayLength = 0 ;

        while (true)
	    {
	    String fore = file.readString() ;
	    if (fore == null)
	        break ;
	    if (arrayLength == array.length)
		{
		System.out.println("ERROR: too many people") ;
		System.exit(1) ;
		}
            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 ;
            array[arrayLength] = new Person(fore, sur, age, gender) ;
	    arrayLength++ ;
	    }
        file.closeFile() ;
	return arrayLength ;
	} // end of method readArray

    /**
     *
     * displayArray
     *
     */

    private static void displayArray(Person[] array, int arrayLength)
        {
        for (int i = 0 ; i < arrayLength ; i++)
    	    System.out.println(i + ": " + array[i].getForename() + " " +
		array[i].getSurname() + " " + array[i].getAge()) ;
        } // end of method displayArray

    /*
     *
     * sortArray
     *
     */

    private static void sortArray(Person[] array, int arrayLength)
        { 
        for (int i = 1 ; i < arrayLength ; i++)
	    {
	    int j = i ;
	    String s = array[i].getSurname() ;
	    Person p = array[i] ;
	    while ((j > 0) &&
                   (array[j - 1].getSurname().compareTo(s) > 0))
	        {
	        array[j] = array[j - 1] ;
	        j-- ;
	        }
            array[j] = p ;
	    }
        } // end of method sortArray

    /**
     *
     * searchArray
     *
     */

    private static void searchArray(Person[] array, int arrayLength)
			throws IOException
        {
        BasicIo.prompt("Type the surname to be searched for: ") ;
        String surname = BasicIo.readString() ;
        int i = -1 ;
        int j = arrayLength ;
        int k = 0 ;
        boolean matchSurname = false ;
        while (((i + 1) < j) && (!matchSurname))
	    {
	    k = (i + j) / 2 ;
	    int result = array[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 searchArray

    } // end of class Chapter9n5