ERROR: Couldn't read row 0, col -1 from CursorWindow. Make sure the Cursor is correctly initialized before accessing data

问题

I have created a very simple database android app. It takes an input and display result. Add button is used to add the input and delete button for deleting the input stored in SQLite database. My cursor in Android SQLite is pointed correctly but still I am facing the error: Caused by: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it. Following is the cursor part: Cursor c = db.rawQuery(query, null);

    c.moveToFirst();

    //Traversing through DB
    while (!c.isAfterLast()){
        if(c.getString(c.getColumnIndex("studentname")) !=null)
        {
            dbString += c.getString(c.getColumnIndex("studentname"));
            dbString +="\n"; }

        c.moveToNext(); }
        db.close();

        return dbString;

I have tried changing cursor positions but still same error appearing. I have researched on other sites and same is the concept but still there is an issue.

回答1:

Apparently, there is no studentname column in your result set, if c.getColumnIndex("studentname") is returning -1.

回答2:

As mentioned above by CommonsWare, this apparently look like that there is no column of such name and its absolutely true. My column name is StudentName, not studentname, hence there was a mistake with respect to the proper column name, which resulted in to -1 (No column at all to work on). Thanks CommonsWare for pointing out my silly mistake :)

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来源：https://stackoverflow.com/questions/38819232/error-couldnt-read-row-0-col-1-from-cursorwindow-make-sure-the-cursor-is-co