The Big Programming Thread - Page 409

        // get rest of list
	// note: this operation must create a new list (which may be empty = null)
	PlayerList tail()
        {
		PlayerList list = new PlayerList(head().getNext());
		if(list.head() == null)
                {
			PlayerList empty = new PlayerList();
			return empty;
		}
		return list;
	
	}

	// constructor for empty list
	PlayerList()
	{
		firstPlayer = null;
	}
	
	// constructor to start list with first player
	PlayerList(Player playr)
	{
		firstPlayer = playr;
	}

public class PlayerList
{
	private Player firstPlayer;

	// constructor for empty list
	PlayerList()
	{
		firstPlayer = null;
	}
	
	// constructor to start list with first player
	PlayerList(Player playr)
	{
		firstPlayer = playr;
	}
	
	// *************************************************************************
	// setter for first element
	void setHead(Player playr)
	{
		firstPlayer = playr;
	}
	
	// *************************************************************************
	// getter for first element
	Player head()
	{
		return firstPlayer;
	}

	// *************************************************************************
	// get rest of list
	// note: this operation must create a new list (which may be empty = null)
	PlayerList tail()
	{
		PlayerList list = new PlayerList(head().getNext());
		if(list.head() == null){
			final PlayerList empty = new PlayerList();
			return empty;
		}
		return list;
		
	}
	
	// *************************************************************************
	// add each new Student at the beginning of the list
	void addPlayer(Player playr)
	{
		playr.setNext(head());
		setHead(playr);
	}
	
	// *************************************************************************
	// add each new Student recursively at the end of the list
	void addPlayerLast(Player playr, PlayerList list)
	{
		if(list.head().getNext() == null){
			list.head().setNext(head().getNext());
		}
		else{
			addPlayerLast(playr, tail());
		}
			
	}
	
	// *************************************************************************
	void addPlayerLast(Player playr)
	{
		addPlayerLast(playr, this);
	}
	
	// *************************************************************************
	// recursive print-out of player data (id, family name, first name, goals)
	void printList(PlayerList list)
	{
		if(head() == null){
		 }
		else{
			//System.out.println(head().toString()); 
			printList(tail());
		}
	}
	
	// *************************************************************************
	// just call printList(param) to allow for recursion and to keep the interface clean
	void printList()
	{
		printList(this);
	}
	
	// *************************************************************************
	// recursive computation of length of list
	int lengthList(PlayerList list)
	{
		if(firstPlayer.getNext() == null){
			return 1;
		 }
		else{
			return 1+lengthList(tail());
		}
	}
	
	// *************************************************************************
	int lengthList()
	{
		return lengthList(this);
	}
	
	// *************************************************************************
	// recursive computation of sum of ages of all players in the list
	int sumAge(PlayerList list)
	{
		if(firstPlayer.getNext() == null){
			return firstPlayer.getAge();
		 }
		else{
			
			return head().getAge() + sumAge(tail());	

		}
	}

	// *************************************************************************
	// recursive computation of sum of games of all players in the list
	int sumAge()
	{
		return sumAge(this);
	}

	// *************************************************************************
	/**
	 * @param args
	 */
	public static void main(String[] args)
	{				
		
		PlayerList test = new PlayerList();
		Player ilkay = new Player(1, "Guendokan", "Ilkay", 23, "Stauchung");
		test.addPlayer(ilkay);
		Player mats = new Player(2, "Hummels", "Mats", 24, "Baenderriss");
		test.addPlayer(mats);
		Player neven = new Player(3, "Subotic", "Neven", 25, "Kreuzbandriss");
		test.addPlayer(neven);
		Player sven = new Player(4, "Bender", "Sven", 24, "Innenbandanriss");
		test.addPlayer(sven);
		Player nuri = new Player(5, "Sahin", "Nuri", 25, "Sprunggelenk");
		test.addPlayer(nuri);
		
		System.out.println(test.sumAge());
		System.out.println(test.head().getFamilyName()); // testing

		//players.printList();
		//System.out.println("length of list: " + test.lengthList());
		//System.out.println("average age: " + (double) players.sumAge()/players.lengthList() + "\n");
		
	}
}

public class Player
{
	private int id;
	private String familyName;
	private String firstName;
	private int age;
	private String injury;
	private Player next;
	
	Player(int id, String familyName, String firstName, int age, String injury, Player next)
	{
		this.id = id;
		this.familyName = familyName;
		this.firstName = firstName;
		this.age = age;
		this.injury = injury;
		this.next = next;
	}
	
	Player(int id, String familyName, String firstName, int age, String injury)
	{
		this(id, familyName, firstName, age, injury, null);
	}

	int getId() {
		return id;
	}

	void setId(int id) {
		this.id = id;
	}

	String getFamilyName() {
		return familyName;
	}

	void setFamilyName(String familyName) {
		this.familyName = familyName;
	}

	String getFirstName() {
		return firstName;
	}

	void setFirstName(String firstName) {
		this.firstName = firstName;
	}

	int getAge() {
		return age;
	}

	void setAge(int age) {
		this.age = age;
	}
	
	String getInjury() {
		return injury;
	}

	void setInjury(String injury) {
		this.injury = injury;
	}
	
	Player getNext() {
		return next;
	}

	void setNext(Player next) {
		this.next = next;
	}	
}