import java.util.ArrayList;

// Queue using an ArrayList -- note that the public methods
//   change only by using java.lang.Object instead of int
public class QueueV2
{
  // Constant specifying the maximum queue size
  public static final int DEFAULT_SIZE = 1000;

  // Internal (hidden) representation is an ArrayList
  private ArrayList q;

  // Maximum size of this queue
  private int maxSize;

  // Construct a queue of default size
  public QueueV2() { this( DEFAULT_SIZE ); }

  // Construct a queue
  public QueueV2( int size ) {
    this.q = new ArrayList( size );
    this.maxSize = size;
  }

  // Determine if this queue is empty
  public boolean isEmpty() {
    return this.q.isEmpty();
  }
  
  // Add an element to the end of this queue
  public void add( Object x ) {
    if ( this.q.size() < this.maxSize ) {
      this.q.add( x );
      System.out.println( "ADDED " + x );
    } else {
      // ERROR
      System.out.println( "FULL - CANNOT ADD " + x );
    }
  }
  
  // Remove an element from the head of this queue
  public Object remove() {
    if ( this.q.isEmpty() ) {
      // ERROR
      System.out.println( "EMPTY!" );
      return -1;
    } else {
      Object x = this.q.remove( 0 );  // index 0
      System.out.println( "REMOVED " + x );
      return x;
    }
  }

  // The main() code does not change
  public static void main(String[] args) {
    System.out.println( "Default queue size is " + QueueV2.DEFAULT_SIZE );

    QueueV2 q1 = new QueueV2(3);

    if ( q1.isEmpty() ) {
      q1.add( 12.5 );
      q1.add( "HELLO" );
      Object x = q1.remove();
      q1.add( 36 );
      q1.add( 17 );
      q1.add( 14 );
      x = q1.remove();
      x = q1.remove();
      x = q1.remove();
      x = q1.remove();
    }
  }

}