的NullPointerException獲取Android中

我想在一個對象來獲取數據庫記錄機智htis方法和STOR數據庫信息時：的NullPointerException獲取Android中

SQLiteDatabase db = openOrCreateDatabase("lingodb",MODE_PRIVATE, null);   
    Cursor cur; 
    cur = db.rawQuery("Select * from lingo where stage='1'", null); 

    cur.moveToFirst(); 
    int n=0; 
    while (!cur.isAfterLast()) { 
     words_array[n].word = cur.getString(cur.getColumnIndex("word")); 
     words_array[n].pack = cur.getInt(cur.getColumnIndex("stage")); 
     words_array[n].id = cur.getInt(cur.getColumnIndex("pack_id")); 
     n=n+1; 
     cur.moveToNext(); 
    } 
    cur.close(); 
    db.close();

我在DB信息是有效的，但是這個代碼提供了這樣的錯誤：

04-26 23:15:52.090: E/AndroidRuntime(22002): FATAL EXCEPTION: main 
04-26 23:15:52.090: E/AndroidRuntime(22002): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.english.game/com.english.game.MainActivity}: java.lang.NullPointerException 
    04-26 23:15:52.090: E/AndroidRuntime(22002): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at android.app.ActivityThread.access$600(ActivityThread.java:141) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at android.os.Handler.dispatchMessage(Handler.java:99) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at android.os.Looper.loop(Looper.java:137) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at android.app.ActivityThread.main(ActivityThread.java:5041) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at java.lang.reflect.Method.invokeNative(Native Method) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at java.lang.reflect.Method.invoke(Method.java:511) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at dalvik.system.NativeStart.main(Native Method) 
    04-26 23:15:52.090: E/AndroidRuntime(22002): Caused by: java.lang.NullPointerException 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at com.english.game.MainActivity.onCreate(MainActivity.java:75) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at android.app.Activity.performCreate(Activity.java:5104) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 
    04-26 23:15:52.090: E/AndroidRuntime(22002):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)

爲什麼會發生這種情況？

來源

2013-04-26 Fcoder

什麼是線75 IH MainActivity類別？ – rciovati 2013-04-26 18:52:16

@rciovati：this line：words_array [n] .word = cur.getString（cur.getColumnIndex（「word」））; – Fcoder 2013-04-26 18:54:29

你是否爲words_array分配空間，不是嗎？

在您提供的代碼段中，words_array和cur可能爲空。請確保爲正在填充的陣列分配空間。由於堆棧跟蹤referes到線

words_array[n].word = cur.getString(cur.getColumnIndex("word"))

和cur不能爲空，只能words_array可以爲空

來源

2013-04-26 18:52:35 Blackbelt

是的，我做到了。我的問題是我的問題是從數據庫中獲取信息 – Fcoder 2013-04-26 18:55:44

哇，你做到了。實際上，我忘記了爲words_array分配空間......謝謝我的朋友 – Fcoder 2013-04-26 18:58:08

不客氣。 – Blackbelt 2013-04-26 18:59:02

的NullPointerException獲取Android中

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