Android神秘的空指针异常

Question

由于我已经上传我的应用程序，我收到了很多java.lang.NullPointerException崩溃报告。我很努力地理解这个问题，因为它不会在模拟器或我亲自测试的物理设备上崩溃。下面是报告的一个示例：我相信这是在“practiceSubscreen”当按下“openNumbersSelect”按钮崩溃

java.lang.IllegalStateException: Could not execute method of the activity 
at android.view.View$1.onClick(View.java:2072) 
at android.view.View.performClick(View.java:2408) 
at android.view.View$PerformClick.run(View.java:8817) 
at android.os.Handler.handleCallback(Handler.java:587) 
at android.os.Handler.dispatchMessage(Handler.java:92) 
at android.os.Looper.loop(Looper.java:143) 
at android.app.ActivityThread.main(ActivityThread.java:4914) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:521) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.reflect.InvocationTargetException 
at com.bryan.barrett.countdownforandroid.practiceSubscreen.openNumbersSelect(Unknown   Source) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:521) 
at android.view.View$1.onClick(View.java:2067) 
... 11 more 
Caused by: java.lang.NullPointerException 
... 15 more 

。这是我该按钮的代码：

public void openNumbersSelect(View view){ 
    Intent iNum = new Intent(this, numbersSelect.class); 
    String gamemode = "practice"; //practice mode 
    iNum.putExtra("gamemode", gamemode); 
    startActivity(iNum); 

    overridePendingTransition(R.anim.fadein, R.anim.fadeout); 
    if(sound){ 
     soundPool.play(Main.SNDclick, audio.getStreamVolume(AudioManager.STREAM_MUSIC), 
       audio.getStreamVolume(AudioManager.STREAM_MUSIC), 1, 0, 1f); 
    } 
} 

，这是在以下numbersSelect类，它的目的是打开的onCreate代码：

public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_numbers_select); 

     Intent i = getIntent(); 
     gamemode = i.getStringExtra("gamemode");  
     gameround = i.getIntExtra("gameround", 0) + 1; 
     points = i.getIntExtra("points", 0);  

     //Shared Preferences 
     prefs = PreferenceManager.getDefaultSharedPreferences(this); 
     sound = prefs.getBoolean("sound", true); 

     //Sounds 
     setVolumeControlStream(AudioManager.STREAM_MUSIC); 
     audio = (AudioManager) getSystemService(Context.AUDIO_SERVICE); 
     soundPool = Main.soundPool; 

     //Big Numbers 
     for (int n=25; n<=100; n+=25){  //add 25, 50, 75, 100 
      bignumbers.add(n);    
     } 
     //Small Numbers 
     for (int m=1; m<=10; m++){  //adds 1-10 twice 
      smallnumbers.add(m); 
      smallnumbers.add(m); 
     } 

     //Screen metrics 
     DisplayMetrics metrics = new DisplayMetrics(); 
     getWindowManager().getDefaultDisplay().getMetrics(metrics); 
     int screenw = metrics.widthPixels; int screenh = metrics.heightPixels; 
     int unitw = (screenw/14); int unith = (screenh/40); //divide screen into 14 columns x 40 rows... 

     num1 = (Button)findViewById(R.id.num1img); nums.add(num1); 
     num2 = (Button)findViewById(R.id.num2img); nums.add(num2); 
     num3 = (Button)findViewById(R.id.num3img); nums.add(num3); 
     num4 = (Button)findViewById(R.id.num4img); nums.add(num4); 
     num5 = (Button)findViewById(R.id.num5img); nums.add(num5); 
     num6 = (Button)findViewById(R.id.num6img); nums.add(num6); 
     for(int n=0; n<6; n++){ 
      nums.get(n).setHeight(screenh/4); nums.get(n).setTextSize(Main.fontSize); 
      nums.get(n).setWidth(screenw/6); nums.get(n).setPadding(1, 1, 1, 1); 
     } 
     lrg = (Button)findViewById(R.id.largebutton); lrg.setWidth((unitw*200)/35); 
     sml = (Button)findViewById(R.id.smallbutton); sml.setWidth((unitw*200)/35); 

     Typeface scribble = Typeface.createFromAsset(getAssets(), "fonts/scribble.ttf"); 

     TextView numbersSeltext = (TextView)findViewById(R.id.numbersSeltext); 
     numbersSeltext.setTypeface(scribble); 
     numbersSeltext.setWidth(screenw); numbersSeltext.setHeight(unith*8); 
     if(gamemode.equals("full")){ 
      numbersSeltext.setText("Round " + gameround + ": Select 6 Numbers"); 
     } 
} 

如果任何人都可以在此有何启示这将不胜感激！这是一个令人沮丧的问题，因为它在我已经测试过的设备上完美工作，并且它似乎可以在许多基于反馈的设备上正常工作，因此我甚至不知道代码是否存在问题，或者某些设备是建立..我可以抛出更多的崩溃报告或代码，如果需要的话！

在此先感谢！

Answer 1

如果我是你，我会测试是否所有的Buttons num1，num2 ...和许多其他视图在它们被使用之前都是空的，因为如果视图还没有创建成存在，那么获取视图可能会引发nullpointerexception无论出于何种原因（例如，可滚动列表视图项目只填充可以放入屏幕的视图）。它可能会帮助更多，如果你让使用知道什么是你的布局xml。