android.database.CursorIndexOutOfBoundsException：不知道为什么

Question

我刚刚收到来自使用我的Android应用程序的用户的错误报告。

java.lang.RuntimeException: Unable to start activity ComponentInfo{c`om.gurpswu.gurps/com.gurpswu.gurps.Home}: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2669) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2685) 
at android.app.ActivityThread.access$2300(ActivityThread.java:126) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2038) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:123) 
at android.app.ActivityThread.main(ActivityThread.java:4633) 
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: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0 
at android.database.AbstractCursor.checkPosition(AbstractCursor.java:580) 
at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:214) 
at android.database.AbstractWindowedCursor.getInt(AbstractWindowedCursor.java:84) 
at com.gurpswu.gurps.Player.getIntField(Player.java:137) 
at com.gurpswu.gurps.Home.hudSetup(Home.java:102) 
at com.gurpswu.gurps.Home.onCreate(Home.java:25) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2633) 
... 11 more` 

我还没有能够重新创建问题。我希望你能帮助我。这是我的主屏幕上的代码，从sqlite数据库中检索值。

public String getStringField(String fieldName) { 
     String[] columns = new String[] { KEY_ROWID, KEY_NAME, KEY_CITY, 
       KEY_HEALTH, KEY_ENERGY, KEY_RANK, KEY_CASH, KEY_BALANCE, 
       KEY_DONATED }; 

     Cursor c = ourDatabase.query(true, DATABASE_TABLE, columns, null, null, 
       null, null, "_id DESC", "1"); 

     if (c != null) { 
      c.moveToFirst(); 
      String name = c.getString(c.getColumnIndexOrThrow(fieldName)); 
      c.close(); 
      return name; 
     } 
     return null; 
    } 

    public int getIntField(String fieldName) { 
     String[] columns = new String[] { KEY_ROWID, KEY_NAME, KEY_CITY, 
       KEY_HEALTH, KEY_ENERGY, KEY_RANK, KEY_CASH, KEY_BALANCE, 
       KEY_DONATED }; 

     Cursor c = ourDatabase.query(true, DATABASE_TABLE, columns, null, null, 
       null, null, "_id DESC", "1"); 

     if (c != null) { 
      c.moveToFirst(); 
      int result = c.getInt(c.getColumnIndexOrThrow(fieldName)); 
      c.close(); 
      return result; 
     } 
     return (Integer) null; 
    } 

Answer 1

在堆栈跟踪

，第一行你有CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0。做检查c.getCount()前c.moveToFirst()：

if(c != null) { 
    try { 
     if (c.getCount() > 0) { 
      c.moveToFirst(); 
      return c.getInt(c.getColumnIndexOrThrow(fieldName)); 
     } 
    } 
    finally { 
     c.close(); 
    } 
} 

Answer 2

我的猜测是，你必须检查的c.moveToFirst();的情况下返回值没有任何记录，这应该调用失败（也许返回“falsy”值）

Answer 3

如果什么光标是空的 ？这个如果（C！= NULL）：

更换这一点，如果（！C =空& & c.moveToFirst（））