Question

我正在尝试从Cursor获取结果并将它们放入我创建的Object中。在Eclipse中，似乎光标返回一行（这是我想要的）但是当我尝试访问它时，我收到一个错误。这是获取单行的代码：

public Object fetchIssue(long IssueNumber, int type){

    //Get query cursor.
    Cursor cursor = mDB.query(true, ISSUES_TABLE, ISSUES_COLUMN_ARRAY, COL_ISSUE_ID + "=" + IssueNumber, null, null, null, null, null);

    int iCount = cursor.getCount();

    if(cursor == null)
        return null;

    Object objOut = null;

    if(type == QUERY_TYPE_STRING_ARRAY){
        //Create Array to hold Issue Information.
        String[] IssueInfo = new String[3];
        IssueInfo[0] = String.valueOf(IssueNumber);
        IssueInfo[1] = cursor.getString(cursor.getColumnIndexOrThrow(COL_DATE_RECEIVED));
        IssueInfo[2] = cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_SUMMARY));
        IssueInfo[3] = cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_STATUS));
        IssueInfo[4] = cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_SUB_STATUS));
        IssueInfo[5] = cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_DESCRIPTION));
        objOut = IssueInfo;
    }
    else{
        //Create IssueInfo object.
        IssueInfo IssueInfo = new IssueInfo(
                    IssueNumber, "12/12/2000",
                    //cursor.getString(cursor.getColumnIndexOrThrow(COL_DATE_RECEIVED)),
                    cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_SUMMARY)),
                    cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_STATUS)),
                    cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_SUB_STATUS)),
                    cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_DESCRIPTION)));
        objOut = IssueInfo;
    }

    //Close cursor.
    cursor.close();

    //Return IssueInfo.
    return objOut;
}

iCount返回1，如果我将游标变量放在“变量”窗口中，我可以看到所有列： Cursor variable

并且在类的顶部，表列变量设置为相同的名称：

public static final String ISSUES_TABLE = "Issues";
public static final String COL_ISSUE_ID = "_id";
public static final String COL_DATE_RECEIVED = "DateReceived";
public static final String COL_ISSUE_STATUS = "IssueStatus";
public static final String COL_ISSUE_SUB_STATUS = "IssueSubStatus";
public static final String COL_ISSUE_SUMMARY = "IssueSummary";
public static final String COL_ISSUE_DESCRIPTION = "IssueDescription";

private static final String[] ISSUES_COLUMN_ARRAY = new String[]{
    COL_ISSUE_ID, COL_DATE_RECEIVED, COL_ISSUE_SUMMARY, 
    COL_ISSUE_STATUS, COL_ISSUE_SUB_STATUS, COL_ISSUE_DESCRIPTION};

此行发生错误：

//Create IssueInfo object.
        IssueInfo IssueInfo = new IssueInfo(
                    IssueNumber, "12/12/2000",
                    //cursor.getString(cursor.getColumnIndexOrThrow(COL_DATE_RECEIVED)),
                    cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_SUMMARY)),
                    cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_STATUS)),
                    cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_SUB_STATUS)),
                    cursor.getString(cursor.getColumnIndexOrThrow(COL_ISSUE_DESCRIPTION)));

或其中任何一行（如您所见，我注释掉了收到的日期并在其中放置了一个正常的字符串值，它需要）。

这是错误：

03-13 09:06:42.370: E/AndroidRuntime(2324): FATAL EXCEPTION: AsyncTask #2
    03-13 09:06:42.370: E/AndroidRuntime(2324): java.lang.RuntimeException: An error occured while executing doInBackground()
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at android.os.AsyncTask$3.done(AsyncTask.java:278)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at java.lang.Thread.run(Thread.java:856)
    03-13 09:06:42.370: E/AndroidRuntime(2324): Caused by: android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 1
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at android.database.AbstractCursor.checkPosition(AbstractCursor.java:400)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:136)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:50)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at com.adacel.dashboard.DBAdapter.fetchIssue(DBAdapter.java:215)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at com.adacel.dashboard.IssueInfoCreator.fetchIssue(IssueInfoCreator.java:42)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at com.adacel.dashboard.ViewIssue.LoadIssueDetails(ViewIssue.java:73)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at com.adacel.dashboard.ViewIssue.access$0(ViewIssue.java:70)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at com.adacel.dashboard.ViewIssue$GetIssueDetailsTask.doInBackground(ViewIssue.java:96)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at com.adacel.dashboard.ViewIssue$GetIssueDetailsTask.doInBackground(ViewIssue.java:1)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at android.os.AsyncTask$2.call(AsyncTask.java:264)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
    03-13 09:06:42.370: E/AndroidRuntime(2324):     ... 4 more

非常感谢任何帮助！

Answer 1

您必须先移动到光标的第一个索引：

 cursor.moveToFirst();

Answer 2

尝试修改IssueInfo的大小：

String[] IssueInfo = new String[3];

到

String[] IssueInfo = new String[6];

并将对象IssueInfo的名称更改为其他类似issue_info

Answer 3

在查询之后，始终将光标移动到元素：

if(cursor == null)
    return null;
if(!cursor.moveToFirst()) //this will move the cursor to the first element
    return null;

如果您期望多行，则更好的方法是：

if(cursor != null) {
   cursor.move(-1);
   while(cursor.moveToNext()) {
      //do stuff
   }
}

Android - 光标找不到列

3 个答案: