android - 获取游标中的行数时出错？

Question

我不知道为什么应用程序。当我尝试显示游标内选定行的数量时崩溃。当我评论显示应用程序选定行数的行时。工作正常，否则会崩溃。

代码如下:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    dbd = new DBDemoActivity(this);
    db = dbd.getWritableDatabase();
    cv = new ContentValues();

    cv.put("name", "Amr");
    cv.put("lat", 10);
    cv.put("lng", 20);
    newID = db.insert("Demo", null, cv);

    cv.put("name", "Mikila");
    cv.put("lat", 14);
    cv.put("lng", 22);
    newID = db.insert("Demo", null, cv);

    cv.put("name", "bakri");
    cv.put("lat", 17);
    cv.put("lng", 29);
    newID = db.insert("Demo", null, cv);

    cv.put("name", "geomatics");
    cv.put("lat", 50);
    cv.put("lng", 90);
    newID = db.insert("Demo", null, cv);
    }        

    SQLiteCursor c = (SQLiteCursor) db.rawQuery("SELECT * FROM Demo WHERE lat = 10", null);
    //c.moveToFirst();
    //Toast.makeText(getBaseContext(), c.getCount(), Toast.LENGTH_SHORT).show();
    //dbd.deleteMP(1);   
}   

日志:

02-27 10:46:35.675: E/AndroidRuntime(25525): FATAL EXCEPTION: main
02-27 10:46:35.675: E/AndroidRuntime(25525): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.androidbook.DBDemo/com.androidbook.DBDemo.DemoData}: android.content.res.Resources$NotFoundException: String resource ID #0x9
02-27 10:46:35.675: E/AndroidRuntime(25525):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at android.os.Looper.loop(Looper.java:123)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at android.app.ActivityThread.main(ActivityThread.java:3691)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at java.lang.reflect.Method.invokeNative(Native Method)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at java.lang.reflect.Method.invoke(Method.java:507)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at dalvik.system.NativeStart.main(Native Method)
02-27 10:46:35.675: E/AndroidRuntime(25525): Caused by: android.content.res.Resources$NotFoundException: String resource ID #0x9
02-27 10:46:35.675: E/AndroidRuntime(25525):    at android.content.res.Resources.getText(Resources.java:222)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at android.widget.Toast.makeText(Toast.java:258)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at com.androidbook.DBDemo.DemoData.onCreate(DemoData.java:54)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-27 10:46:35.675: E/AndroidRuntime(25525):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
02-27 10:46:35.675: E/AndroidRuntime(25525):    ... 11 more

Answer 1

问题出在 Toast.makeText 上。makeText() 是一种重载方法，有两种形式 -

makeText(Context c, String s, int duration)

和

makeText(Context, int resId, int duration)

您使用的是第二个(带有 resId 的那个)- 因为 cursor.getCount 返回一个整数。现在 android 正在尝试查找(在您的 Resources 类 @gen 文件夹中)哪个 String 是 cursor.getCount 附属的值。由于找不到，它会抛出 Resources$NotFoundException。

修复:尝试使用 (String.valueOf(cursor.getCount())) 而不是 cursor.getCount()