The

class models a particular way in which an airplane's seats are filled. Here is the class source code:

import java.util.Random;
//size seats, nominally 0-99; patrons are 0-99
public class AirSeating{
  private int size;
  private int[] seats; // if seats[7] holds 4, passenger 4 is in seat 7
  Random ran = new Random();
  
  public AirSeating(int planeSize){
    size = planeSize;
    seats = new int[size];
  }
  
  private void emptyPlane(){
  for(int i = 0; i < size; i++) seats[i] = -1; // start with all at -1
  }
  
  private void seatFirstPerson(){
    // places 0th person in an empty plane
    int firstPersonPos = ran.nextInt(size); // pick random seat for person 0
    seats[firstPersonPos] = 0; // put 0 in chosen seat
  }
  
  private int findKthEmpty(int k){
    /* array seats holds numbers from 0 to size-1 - actual passengers, or -1
    * which means that the seat is empty. What's index of kth empty seat?
    */
    int ctr = k; // tallies number of empties seen as you walk seats 
    int where = 0;
    while (where < size){
     if (empty(where)) // is location "where" empty, that is, -1?
       if (ctr == 0) return where; else ctr--;
     where++;
    } 
    System.out.println("error in findKthEmpty");
    return(-1); // return statement required
  }
  
  private boolean empty(int loc){ 
   // exercise
    
  }
  
  public void fillSeats(){
    /* places all passengers in their seats
     * Variable leftOver holds number of empty seats left on plane
     * pick empty seat n at random: that's where p will go
     */
    emptyPlane(); // build empty plane
    seatFirstPerson(); // places person 0
    int leftOver = size-1; // person 0 already placed
    int n; // will be he kth empty seat
    for(int p = 1; p < size; p++){
      if(empty(p)) {seats[p] = p; leftOver--;} // if p's seat empty: place p
      else {
      n = findKthEmpty(ran.nextInt(leftOver)); 
      seats[n] = p;
      leftOver--; // in loop, after p placed there's one fewer empty seat left
      }
    }
  }
  
  public boolean lastPatronTest(){
    // an exercise
  }
  
  public int printSeat(int who){
    // an exercise
  }
  
  public int ownSeatCount(){
   // an exercise
  }
}

 

Implement the Airseating method empty, lastPatronTest, printSeat and ownSeatCount.