This program demonstrates array manipulation. : Array Insert Remove « Collections Data Structure « Java

1. Java
2. Collections Data Structure
3. Array Insert Remove

This program demonstrates array manipulation.

   
/*
 This program is a part of the companion code for Core Java 8th ed.
 (http://horstmann.com/corejava)

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.util.Arrays;
import java.util.Scanner;

/**
 * This program demonstrates array manipulation.
 * 
 * @version 1.20 2004-02-10
 * @author Cay Horstmann
 */
public class LotteryDrawing {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);

    System.out.print("How many numbers do you need to draw? ");
    int k = in.nextInt();

    System.out.print("What is the highest number you can draw? ");
    int n = in.nextInt();

    // fill an array with numbers 1 2 3 . . . n
    int[] numbers = new int[n];
    for (int i = 0; i < numbers.length; i++)
      numbers[i] = i + 1;

    // draw k numbers and put them into a second array
    int[] result = new int[k];
    for (int i = 0; i < result.length; i++) {
      // make a random index between 0 and n - 1
      int r = (int) (Math.random() * n);

      // pick the element at the random location
      result[i] = numbers[r];

      // move the last element into the random location
      numbers[r] = numbers[n - 1];
      n--;
    }

    // print the sorted array
    Arrays.sort(result);
    System.out.println("Bet the following combination. It'll make you rich!");
    for (int r : result)
      System.out.println(r);
  }
}

   
    
    
  

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