我一直在尝试用Java进行纸牌游戏，但有些人一直在尝试下降。这个游戏中有奇数个玩家，他们每个人都有一张卡队列，第一个玩家是卡队列是空胜。每次我编译它继续给我java.lang.NullPointerException错误。谢谢你的帮助。
package cardgame;
import unit4.collectionsLib.Queue;//importing the queue
public class Main {
public static boolean checkIsEmpty(Queue<Player> p){
boolean is=false;
p.insert(null);
while(p.head()!=null){
if(p.head().getC().isEmpty()){
is=false;
p.insert(p.remove());
}
}
p.remove();
return is;
}
public static int whoWin(Queue<Player> p){
p.insert(null);
while(p.head()!=null){
if(p.head().getC().isEmpty()){
return p.head().getIndex();
}
}
return 0;
}
public static void main(String[] args) {
Queue<Player> players = new Queue(); //queue of players
for(int i=0;i<5;i++){
players.insert(new Player());
}
boolean isOver=false;
while(!isOver)
//the game is over when one player finished his cards
{
Player p = players.remove();
if(p.getC().head().greater(players.head().getC().head())==1){
p.getC().remove();
players.insert(p);
players.insert(players.remove());
}
else if(p.getC().head().greater(players.head().getC().head())==2){
players.head().getC().remove();
players.insert(p);
players.insert(players.remove());
}
else{
players.head().getC().remove();
p.getC().remove();
players.insert(p);
players.insert(players.remove());
}
if(checkIsEmpty(players)){
isOver=true;
System.out.println("the winner in this game is player number :"+whoWin(players));
}
}
}
}
package cardgame;
import unit4.collectionsLib.Queue;
public class Player {
static int autonum=1;
private Queue<Card> c;
private int index;
public Player()
{
for(int i=0;i<7;i++){
c.insert(new Card());}
this.index=autonum;
autonum++;
}
/**
* @return the c
*/
public Queue<Card> getC() {
return c;
}
/**
* @param c the c to set
*/
public void setC(Queue<Card> c) {
this.c = c;
}
public int getIndex(){
return this.index;
}
}
package cardgame;
import java.util.Random;
public class Card {
private int num ;
private int shape;
public Card()
{
Random r = new Random();
this.num = r.nextInt(9)+1;
this.shape = r.nextInt(4)+1;
}
public int greater(Card c){
if(c.getNum()<this.num)
return 1;
else {
if(c.getNum()>this.num){
return 2;
}
else{
if(c.getShape()>c.shape){
return 2;
}
else{
if(c.getShape()<c.shape){
return 1;
}
else{
return 0;
}
}
}
}
}
/**
* @return the num
*/
public int getNum() {
return num;
}
/**
* @param num the num to set
*/
public void setNum(int num) {
this.num = num;
}
/**
* @return the shape
*/
public int getShape() {
return shape;
}
/**
* @param shape the shape to set
*/
public void setShape(int shape) {
this.shape = shape;
}
}