Question

我实际上遇到了三个java.langNullPointerException错误，但是其中两个是相同的，所以如果我修复了一个，我会修复另一个错误。

我正在尝试制作一个Game Class来传递gameTest

以下是我的游戏类的代码

public class Game implements CribbageConstants {

    private Player player1, player2;
    private boolean player1Deals;
    private Game game;

    /**
     * No argument constructor - set default values for Game
     */
    public Game() {
        player1 = player1;
        player1 = player2;
        player1Deals = true;



    }

    // convenience constructor
    public Game(Player player1, Player player2) {
        this.player1 = player1;
        this.player2 = player2;
        this.player1Deals = true;

    }

    //mutator
    public void setPlayer1(Player player1) {
        this.player1 = player1;

    }

    public void setPlayer2(Player player2) {
        this.player2 = player2;
    }

    public void setPlayer1Deals(boolean player1Deals) {
        this.player1Deals = player1Deals;
    }

    public void setGame(Game game) {
        this.game = game;
    }

    //utility methods
    public Player getPlayer1() {
        return player1;
    }

    public Player getPlayer2() {
        return player2;
    }

    /**
     * @return the player1Deals
     */
    public boolean isPlayer1Deals() {
        return player1Deals;
    }

    /**
     * @return the game
     */
    public Game getGame() {
        return game;
    }
}

我在以下代码的第86行收到一个NullPointerException：

//79    public void testSetPlayer1() {
//80        System.out.println("setPlayer1");
//81        Game instance = new Game();
//82        Player p1 = new Player("Jim");
//83        p1.setHand(hand1);
//84        Player p2 = new Player("George");
//85        p2.setHand(hand2);
//86        assertEquals("?", instance.getPlayer1().getName());
//87        instance.setPlayer1(p1);
//88        assertEquals("Jim", instance.getPlayer1().getName());
    }

我在testNoArgConstructor上遇到一个NullPointerException（第54行）

//51    public void testNoArgConstructor() {
//52       System.out.println("Game");
//53       Game instance = new Game();
//54       assertEquals("?", instance.getPlayer1().getName());
//55       assertEquals("?", instance.getPlayer2().getName());
//56       assertEquals(true, instance.isPlayer1Deals());
//57   }

Answer 1

您没有在player1（）`

之前设置变量instance.getPlayer

//79    public void testSetPlayer1() {
//80        System.out.println("setPlayer1");
//81        Game instance = new Game();
//82        Player p1 = new Player("Jim");

            instance.setPlayer1(p1);

//83        p1.setHand(hand1);
//84        Player p2 = new Player("George");
//85        p2.setHand(hand2);
//86        assertEquals("?", instance.getPlayer1().getName());
//87        instance.setPlayer1(p1);
//88        assertEquals("Jim", instance.getPlayer1().getName());
    }

在这两种情况下你都有同样的问题。

//51    public void testNoArgConstructor() {
//52       System.out.println("Game");
//53       Game instance = new Game();

           instance.setPlayer1(new Player("Player One");
//54       assertEquals("?", instance.getPlayer1().getName());

           instance.setPlayer2(new Player("Player Two");
//55       assertEquals("?", instance.getPlayer2().getName());
//56       assertEquals(true, instance.isPlayer1Deals());
//57   }

如果您无法编辑测试用例，可以尝试Game

中变量的默认值

public Game() {
        player1 = new Player("?");
        player1 = new Player("?");
        player1Deals = true;



    }

Answer 2

您已经创建了一个游戏实例但是您从未实例化任何玩家，所以当您使用getPlayer1()时，没有玩家。

在创建游戏后但在引用instanse.setPlayer1(new Player());之前调用getPlayer()。

Answer 3

沿着桌子走一小段路，看看......

Game instance = new Game();
// instance.player1 and instance.player2 are null...

Player p1 = new Player("Jim");
p1.setHand(hand1);
Player p2 = new Player("George");
p2.setHand(hand2);

// instance.player1 and instance.player2 are still null...
// Break here...
assertEquals("?", instance.getPlayer1().getName());
instance.setPlayer1(p1);

如果您要将代码更改为更像......

Game instance = new Game();

Player p1 = new Player("Jim");
p1.setHand(hand1);
Player p2 = new Player("George");
p2.setHand(hand2);

instance.setPlayer1(p1);
assertEquals("?", instance.getPlayer1().getName());

你可能会有更多的成功......

这就是......

Game instance = new Game();
assertEquals("?", instance.getPlayer1().getName());
assertEquals("?", instance.getPlayer2().getName());
assertEquals(true, instance.isPlayer1Deals());

是同一问题的症状，instance.player1和instance.player2都是null

我“认为”你的困惑正在冒出来......

public Game() {
    player1 = player1;
    player1 = player2; // Not sure if this is correct...
    player1Deals = true;
}

什么都不做什么都没有......

这实际上与说...

相同

public Game() {
    player1 = null;
    player1 = null;
    player1Deals = true;
}

Answer 4

我认为您的getPlayer1()功能属于Player类型，因此您应该使用p1.getPlayer1()。您instance是Game()类型。而且，我认为您的功能getName()应定义为Player类型。

两个java.lang.NullPointerException错误

4 个答案: