/** * Question 4 * * * This question is about a data structure that closely resembles a sushi * train. * * A sushi train is a continuously moving belt with a N holders, each designed * to hold a plate of sushi. Sushi plates are added or removed at the kitchen * (position 0), and may be removed by customers at any other position * (1 to N - 1), as the belt passes by. * * The data structure has the concept of holders (which move on the belt), and * positions, which are fixed, with the holders continuously moving past. There * are the same number of positions and holders. * * Each holder may be either empty or hold a single object of type T. * * Objects can only be added at position 0, and only when there is an * empty holder in that position. * * Objects can be removed at any position. * * The belt can advance. Each time it advances, all holders move forward * one position modulus the number of positions in the train. */ public class Q4SushiTrain { /** * Create a SushiTrain of a given size. * * @param size the number of positions (and holders) in the SushiBelt */ public Q4SushiTrain(int size) { // FIXME complete this constructor } /** * @return true if this sushi belt is empty, that is, if * every holder is empty */ public boolean isEmpty() { // FIXME complete this method return false; } /** * If the holder at position 0 is empty, add the given object into the * holder and return true; otherwise return false. * * @param obj the object to add to the belt; must not be null * @return true if the object was added */ public boolean add(T obj) { // FIXME complete this method return false; } /** * If the holder at position pos is not empty, remove the object from the * holder at position pos, and return it. Otherwise, return null. * * @param pos the position from which to remove the object * @return the object that was in the holder at position pos, or null if * there is no such object */ public T remove(int pos) { // FIXME complete this method return null; } /** * Advance the sushi train, moving all holders forward by one position. * The holder at position N-1 moves to position 0. The holder at position * 0 moves to position 1, etc. */ public void advance() { // FIXME complete this method } /** * Check whether a given value is contained in this sushi train. * * Specifically, return true if value is not null and an element e is * contained in this sushi belt such that e.equals(value). * * @param value the value to search for * @return true if the value is contained in this sushi train */ public boolean contains(T value) { // FIXME complete this method return false; } /** * Create a String representation of this sushi train. * * Objects are listed in position order around the train, starting with the * object in the holder at position 0, then the object in the holder * at position 1, etc. * * Values in the train are separated by commas (without spaces). * Each value is converted to string as by {@link String#valueOf(Object)}. * If a holder is empty (null), its value is represented by the empty string, * still including a comma to mark its place in the train. * For example, a train of size five in which: * - the holder at position 0 contains "b" * - the holder at position 1 contains "c" * - the holder at position 2 is empty * - the holder at position 3 is empty * - the holder at position 4 is empty contains "a" * would be represented as "b,c,,,a". * A train of size three where the holder at position 0 contains "zz" and the * other holders are empty would be represented as "zz,,". * An empty train of size seven would be represented as ",,,,,,". * * @return a String representation of this sushi train */ public String toString() { // FIXME complete this method return null; } } 

//////////// WARNING DO NOT USE (ARRAY-LIST OR ANY JAVA.UTIL.LIST) COLLECTION FOR THIS QUESTION ////////////