当我从另一个 java 文件调用一个类时，Android 程序崩溃

Question

我是 android 开发和 java 编程的新手，但我决定在 android 中编写一个饮酒游戏应用程序。这个应用程序基本上模拟一副牌，玩家点击一个按钮来抽一张牌，然后根据抽出的牌，玩家玩一个喝酒游戏(即喝 1 杯酒，喝 2 杯酒......等)。

我在一个 java 文件中有主程序，在另一个 java 文件中有洗牌并将卡片序列放入数组中的代码。我的问题是，每当从主程序 (fubar.java) 调用另一个 java 文件 (classicMode.java) 中的类时，我的 android 程序就会崩溃并给出错误:

“应用程序 Drinking Game - FUBAR(进程 com.games.dg)意外停止。请重试”。

主程序代码如下:

package com.games.dg;

import java.util.Arrays;
import java.util.Collections;

import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
import android.widget.TextView;
import android.view.View;
import android.view.View.OnClickListener;
import com.games.dg.classicMode;

public class fubar extends Activity 
{
    private Button classic;
    private Button custom;
    private Button help;
    private Button back;
    private Button showCard;
    private TextView txtbox;
    private int showCardClick = 0;
    private classicMode newGame;
    String[] cardDeck;



    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        initControls();
    }

    public void initControls()
    {
     classic = (Button)findViewById(R.id.classicGame);
     custom = (Button)findViewById(R.id.customGame);
     help = (Button)findViewById(R.id.gameHelp);



     // Classic Game is Selected
     classic.setOnClickListener(new OnClickListener()
     {
      public void onClick (View v)
      {
       setContentView(R.layout.gamegui);
    cardDeck = newGame.getCards();

       // Back Button Clicked
       back = (Button)findViewById(R.id.backButton);
       back.setOnClickListener(new OnClickListener()
       {
        public void onClick (View v)
        {
         setContentView(R.layout.main);
         initControls();
         showCardClick = 0;
        }
       });

       //start the game method here
       showCard = (Button)findViewById(R.id.showCard);
       txtbox = (TextView)findViewById(R.id.textBox);
       showCard.setOnClickListener(new OnClickListener()
       {
        public void onClick (View v)
        {
         if (showCardClick <=51)
         {
          txtbox.setText(cardDeck[showCardClick]);
             showCardClick++;
         }
         else
          txtbox.setText("End of Game");

        }
       });
            }
}

下面是我其他类(class)洗牌的代码:

package com.games.dg;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

class classicMode
{

 // Variables that describe number of cards and array cards will be placed in

 public int cardCount = 52;
 public static int[][] cards;



 // Variables that describe the rules when a certain card is drawn
 public String ace = "Take 1 Drink!";
 public String two = "Take 2 Drinks!!";
 public String three = "Take 3 Drinks!!!";
 public String four = "Questions: The Dealer must ask the group a question, everyone else must answer his question with a question of their own...";
 public String five = "Take 5 Drinks!!!!!";
 public String six = "I Never....: The person who draws this card must tell the group something he or she has never done, anyone in the group who did what the dealer has'nt takes a drink";
 public String seven = "Thumbmaster: The person who draws this card is the Thumbmaster for the entire game. Everytime he or she puts his thumb on the table, everyone else must follow. The last person to do so takes  a drink.";
 public String eight = "The Categories!: The Dealer must give a category to the group, the group must then mention brands within that category. (Ex. Dealer says: Cars, brands would be honda, toyota, mazda...)";
 public String nine = "Its Rhyme Time: The Dealer says a word, everyone else in the group must come up with a rhyme for that word, the loser takes a drink";
 public String ten = "Everyone Drinks!";
 public String jack = "Dude's Night Out: All the guys take a drink";
 public String queen = "Ladies Drink for Free: All the girls take a drink";
 public String king = "The Waterfall: The Dealer starts drinking, then another person, then a 3rd person and so on. The second person can not stop drinking until the first person stops, the third person cant stop until the second one stops, and so on. Pray that a heavy drinker doesnt go first!";


 // Shuffles the 2D card matrix, in the matrix each number represents a card

public static void mixup()
 {
  int[] values = {1,2,3,4,5,6,7,8,9,10,11,12,13};
  for(int i=0;i<=3;i++)
  {
   Collections.shuffle(Arrays.asList(values));
   for(int j=0;j<=12;j++)
    cards[j][i]=values[j];
  }

 }

 //Outputs the card order as a 1D array of strings

public String[] getCards()
 {
  String[] card_deck = new String[52];
  int k = 0;
  mixup();

  for(int i=0;i<=12;i++)
  {
   for(int j=0;j<=3;j++)
   {
    if(j==0)
    {
     card_deck[k] = Integer.toString(cards[i][j]) + "of Hearts";
     k++;
    }
    if (j==1)
    {
     card_deck[k] = Integer.toString(cards[i][j]) + "of Spades";
     k++;
    }
    if (j==2)
    {
     card_deck[k] = Integer.toString(cards[i][j]) + "of Clubs";
     k++;
    }
    if (j==3)
    {
     card_deck[k] = Integer.toString(cards[i][j]) + "of Diamonds";
     k++;
    }

   }
  }

  return card_deck;
 }




}

例如，当调用“cardDeck = newGame.getCards();”时或“txtbox.setText(cardDeck[showCardClick]);”制作完成，程序崩溃/谁能帮帮我？

提前致谢!

更新，这是我在程序启动时发生的事情的日志:

D/HomeLoaders(   93):   ----> cleared application list
I/ActivityManager(   50): Displayed activity com.games.dg/.fubar: 1360 ms (total 1360 ms)
D/KeyguardViewMediator(   50): pokeWakelock(5000)
I/ARMAssembler(   50): generated scanline__00000077:03545404_00000A04_00000000 [ 29 ipp] (51 ins) at [0x2d1320:0x2d13ec] in 4688047 ns
I/ActivityManager(   50): Start proc com.android.inputmethod.latin for service com.android.inputmethod.latin/.LatinIME: pid=235 uid=10001 gids={3003, 1015}
D/ddm-heap(  235): Got feature list request
D/dalvikvm(  235): Trying to load lib /system/lib/libjni_latinime.so 0x43758040
D/dalvikvm(  235): Added shared lib /system/lib/libjni_latinime.so 0x43758040
D/AndroidRuntime(  221): Shutting down VM
W/dalvikvm(  221): threadid=3: thread exiting with uncaught exception (group=0x4001aa28)
E/AndroidRuntime(  221): Uncaught handler: thread main exiting due to uncaught exception
E/AndroidRuntime(  221): java.lang.NullPointerException
E/AndroidRuntime(  221):    at com.games.dg.classicMode.mixup(classicMode.java:42)
E/AndroidRuntime(  221):    at com.games.dg.classicMode.getCards(classicMode.java:52)
E/AndroidRuntime(  221):    at com.games.dg.fubar$1.onClick(fubar.java:49)
E/AndroidRuntime(  221):    at android.view.View.performClick(View.java:2344)
E/AndroidRuntime(  221):    at android.view.View.onTouchEvent(View.java:4133)
E/AndroidRuntime(  221):    at android.widget.TextView.onTouchEvent(TextView.java:6510)
E/AndroidRuntime(  221):    at android.view.View.dispatchTouchEvent(View.java:3672)
E/AndroidRuntime(  221):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
E/AndroidRuntime(  221):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
E/AndroidRuntime(  221):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
E/AndroidRuntime(  221):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
E/AndroidRuntime(  221):    at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1712)
E/AndroidRuntime(  221):    at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1202)
E/AndroidRuntime(  221):    at android.app.Activity.dispatchTouchEvent(Activity.java:1987)
E/AndroidRuntime(  221):    at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1696)
E/AndroidRuntime(  221):    at android.view.ViewRoot.handleMessage(ViewRoot.java:1658)
E/AndroidRuntime(  221):    at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(  221):    at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime(  221):    at android.app.ActivityThread.main(ActivityThread.java:4203)
E/AndroidRuntime(  221):    at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(  221):    at java.lang.reflect.Method.invoke(Method.java:521)
E/AndroidRuntime(  221):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
E/AndroidRuntime(  221):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
E/AndroidRuntime(  221):    at dalvik.system.NativeStart.main(Native Method)
I/Process (   50): Sending signal. PID: 221 SIG: 3
I/dalvikvm(  221): threadid=7: reacting to signal 3
E/dalvikvm(  221): Unable to open stack trace file '/data/anr/traces.txt': Permission denied
I/ARMAssembler(   50): generated scanline__00000077:03515104_00000000_00000000 [ 27 ipp] (41 ins) at [0x34aa18:0x34aabc] in 572941 ns
I/ARMAssembler(   50): generated scanline__00000077:03515104_00001001_00000000 [ 64 ipp] (84 ins) at [0x34aac0:0x34ac10] in 1098617 ns
I/Process (  221): Sending signal. PID: 221 SIG: 9
I/ActivityManager(   50): Process com.games.dg (pid 221) has died.
I/WindowManager(   50): WIN DEATH: Window{43949420 com.games.dg/com.games.dg.fubar paused=false}
W/UsageStats(   50): Unexpected resume of com.android.launcher while already resumed in com.games.dg
W/InputManagerService(   50): Got RemoteException sending setActive(false) notification to pid 221 uid 10022

Answer 1

您从未真正初始化过这些引用。这与 C++ 中的 Button button 实际上会创建 Button 类型的实例有点不同。在 Java 中，Button button 只是创建对它的引用，所以你需要说

newGame = new classicMode();

在你的 onCreate() 中(或者你甚至可以像那样初始化它)。顺便说一句，Java 约定总是让类名以大写开头。

更新:既然您发布了 logcat，问题出在卡片数组上。它是一个数组的数组，所以你需要初始化外部数组，然后是内部数组，即

cards = new int[52][];

for (int x=0; x<52; x++) {
    cards[x] = new int[52];
}

或

cards = new int[52][52];

我并没有仔细查看您的代码，但我应该提一下，这种方法似乎效率很低，就像为每种卡片类型创建一个字符串一样。您应该改为在运行时创建字符串。