/**

* This class is revised from the RandomNumbers.java from the Weiss book, "Data Structures & Problem Solving Using Java" (4th edition).

* It demonstrate how to use the sort() and binarySearch() methods with Integer Arrays.

**/

import java.util.Random;

import java.util.Arrays;

import java.util.Collections;

public class RandomNumbers2

{

// Generate random numbers (from 1 to DIFF_NUMBERS)

// Print number of occurrences of each number

public static final int DIFF_NUMBERS = 10;

public static final int TOTAL_NUMBERS = 10000;

private static void display (Integer [] ar) {

System.out.println( Arrays.toString(ar) );

}

public static void main( String [ ] args )

{

// Create the array of Integer; initialize to zero

Integer [ ] numbers = new Integer[ DIFF_NUMBERS + 1 ];

for( int i = 0; i < numbers.length; i++ )

numbers[ i ] = 0;

Random r = new Random( );

// Generate the numbers

for( int i = 0; i < TOTAL_NUMBERS; i++ )

numbers[ r.nextInt( DIFF_NUMBERS ) + 1 ]++;

display (numbers);

Arrays.sort(numbers); // sorting the numbers in the array into ascending order

System.out.println ("After sorting ...");

display (numbers);

int position = Arrays.binarySearch(numbers, TOTAL_NUMBERS / DIFF_NUMBERS); // search the array using binary search

if ( position < 0 )

System.out.println(TOTAL_NUMBERS / DIFF_NUMBERS + " is not found in the array.");

else

System.out.println (TOTAL_NUMBERS / DIFF_NUMBERS + " is at position " + position);

Arrays.sort(numbers, Collections.reverseOrder()); // sorting the numbers in the array into descending order

//reverseOrder() is a method defined in the Collections class

// Collections.reverse(Arrays.asList(numbers)); //somehow this does not work!?

System.out.println("\nAfter reverse sorting -----------");

display (numbers);

position = Arrays.binarySearch(numbers, TOTAL_NUMBERS / DIFF_NUMBERS); // search the array using binary search

if ( position < 0 )

System.out.println(TOTAL_NUMBERS / DIFF_NUMBERS + " is not found in the array.");

else

System.out.println (TOTAL_NUMBERS / DIFF_NUMBERS + " is at position " + position);

} // main

}