IllegalArgumentException：无效的列

Question

这是logcat：

01-15 16:06:03.622: ERROR/AndroidRuntime(22300): Uncaught handler: thread main exiting due to uncaught exception
01-15 16:06:03.657: ERROR/AndroidRuntime(22300): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mohit.geo2do/com.mohit.geo2do.activities.TaskEdit}: java.lang.IllegalArgumentException: Invalid column due_date
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2496)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.app.ActivityThread.access$2200(ActivityThread.java:119)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.os.Looper.loop(Looper.java:123)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.app.ActivityThread.main(ActivityThread.java:4363)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at java.lang.reflect.Method.invokeNative(Native Method)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at java.lang.reflect.Method.invoke(Method.java:521)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:862)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:620)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at dalvik.system.NativeStart.main(Native Method)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300): Caused by: java.lang.IllegalArgumentException: Invalid column due_date
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.database.sqlite.SQLiteQueryBuilder.computeProjection(SQLiteQueryBuilder.java:508)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.database.sqlite.SQLiteQueryBuilder.buildQuery(SQLiteQueryBuilder.java:356)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.database.sqlite.SQLiteQueryBuilder.query(SQLiteQueryBuilder.java:309)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.database.sqlite.SQLiteQueryBuilder.query(SQLiteQueryBuilder.java:266)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at com.mohit.geo2do.provider.TasksProvider.query(TasksProvider.java:174)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.content.ContentProvider$Transport.query(ContentProvider.java:130)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.content.ContentResolver.query(ContentResolver.java:202)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at com.mohit.geo2do.activities.TaskEdit.onCreate(TaskEdit.java:105)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-15 16:06:03.657: ERROR/AndroidRuntime(22300):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)

与之关联的行是：

private Cursor task;
private Uri uri;
private String[] PROJECTION { 
    Tasks._ID, Tasks.TITLE, Tasks.COMPLETED, Tasks.DUE_DATE, Tasks.IMPORTANCE, Tasks.NOTES
};
...
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.edit_task);
    ...
    uri = getIntent().getData();
    task = getContentResolver().query(uri, PROJECTION, null, null, null);
} 
...

可能是什么问题呢？创建数据库就好了。您还需要查看其他代码吗？

更新：
我非常确定此列存在。我用这个查询数据库：

Cursor c = db.rawQuery("SELECT * FROM tasks LIMIT 1", null);
for (int i = 0; i < c.getColumnNames().length; i++) {
    Log.v(TAG, c.getColumnNames()[i]);
}

在LogCat中：

01-15 16:52:07.857: VERBOSE/TasksProvider(24325): Creating database...
01-15 16:52:07.862: VERBOSE/TasksProvider(24325): _id
01-15 16:52:07.862: VERBOSE/TasksProvider(24325): title
01-15 16:52:07.862: VERBOSE/TasksProvider(24325): completed
01-15 16:52:07.862: VERBOSE/TasksProvider(24325): due_date
01-15 16:52:07.862: VERBOSE/TasksProvider(24325): notes
01-15 16:52:07.862: VERBOSE/TasksProvider(24325): importance

因此该列确实存在。

Answer 1

我发现了一个奇怪的解决方案。在中String[] PROJECTION。你所要做的：

private String[] PROJECTION { 
    Tasks._ID, 
    Tasks.TITLE, 
    Tasks.COMPLETED,
    Tasks.DUE_DATE + " as " + Tasks.DUE_DATE, 
    Tasks.IMPORTANCE + " as " + Tasks.DUE_DATE, 
    Tasks.NOTES + " as " + Tasks.NOTES
};