내 안드로이드 애플 리케이션의 치명적인 예외

Question

nullpointer 예외로 인해 발생하는 것으로 보이는 치명적인 예외가 발생합니다. Logcat은 내 onCreate 메소드에있는 Java 행 39를 가리키고 있습니다. 여기에 내 onCreate 변수와 전역 변수가 있습니다.

GestureLibrary mLibrary = GestureLibraries.fromRawResource(this, R.raw.gestures); 
    Resources res; 
    String [] letters; 
    int i = 1; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) 
    { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     if (!mLibrary.load()) 
     { 
      finish(); 
     } 


     res = getResources(); 
     letters = res.getStringArray(R.array.LetterToBeDrawn); 
     TextView tv = (TextView) findViewById(R.id.text); 
     tv.setText("Draw the letter: "+letters[i]); 

     GestureOverlayView gestures = (GestureOverlayView)findViewById(R.id.gestures); 
     gestures.addOnGesturePerformedListener(this); 
    } 

이 모든 것이 나에게 좋을 것 같아서 왜 nullpointer 예외가 발생하는지 알 수 없습니다. 내 xml 파일뿐만 아니라 나에게 잘 보이는 :

<android.gesture.GestureOverlayView 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:id="@+id/gestures" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    android:fadeOffset="1000" 
    android:gestureStrokeType="multiple" 
    tools:context=".MainActivity" > 

    <TextView 
     android:id="@+id/text" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     /> 

</android.gesture.GestureOverlayView> 

로그 캣 :

04-30 10:48:48.418: D/dalvikvm(1465): GC_FOR_ALLOC freed 248K, 10% free 3137K/3452K, paused 86ms, total 96ms 
04-30 10:48:48.418: D/AndroidRuntime(1465): Shutting down VM 
04-30 10:48:48.428: W/dalvikvm(1465): threadid=1: thread exiting with uncaught exception (group=0xb1a84ba8) 
04-30 10:48:48.468: E/AndroidRuntime(1465): FATAL EXCEPTION: main 
04-30 10:48:48.468: E/AndroidRuntime(1465): Process: com.gmail.Sheridjohn.letterchecker, PID: 1465 
04-30 10:48:48.468: E/AndroidRuntime(1465): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.gmail.Sheridjohn.letterchecker/com.gmail.Sheridjohn.letterchecker.MainActivity}: java.lang.NullPointerException 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at android.app.ActivityThread.access$800(ActivityThread.java:135) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at android.os.Handler.dispatchMessage(Handler.java:102) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at android.os.Looper.loop(Looper.java:136) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at android.app.ActivityThread.main(ActivityThread.java:5017) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at java.lang.reflect.Method.invoke(Method.java:515) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at dalvik.system.NativeStart.main(Native Method) 
04-30 10:48:48.468: E/AndroidRuntime(1465): Caused by: java.lang.NullPointerException 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at com.gmail.Sheridjohn.letterchecker.MainActivity.onCreate(MainActivity.java:39) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at android.app.Activity.performCreate(Activity.java:5231) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159) 
04-30 10:48:48.468: E/AndroidRuntime(1465):  ... 11 more 
04-30 10:48:54.378: I/Process(1465): Sending signal. PID: 1465 SIG: 9 

편집 : 나는 mLibrary 다음 널 (null) 내에서 OnCreate에서 그것을 초기화로 변경했지만 여전히입니다 라인 (39)에 깨고 :

tv.setText("Draw the letter: "+letters[i]); 

Answer 1

첫 번째 문제는 여기에 있습니다 :

GestureLibrary mLibrary = GestureLibraries.fromRawResource(this, R.raw.gestures); 

올바른 방법은 다음과 같습니다.

GestureLibrary mLibrary = null; 
Resources res; 
String [] letters; 
int i = 1; 

@Override 
protected void onCreate(Bundle savedInstanceState) 
{ 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    mLibrary = GestureLibraries.fromRawResource(this, R.raw.gestures); 

    if (!mLibrary.load()) 
    { 
     finish(); 
    } 


    res = getResources(); 
    letters = res.getStringArray(R.array.LetterToBeDrawn); 
    TextView tv = (TextView) findViewById(R.id.text); 
    tv.setText("Draw the letter: "+letters[i]); 

    GestureOverlayView gestures = (GestureOverlayView)findViewById(R.id.gestures); 
    gestures.addOnGesturePerformedListener(this); 
}