Android - 为什么我在SQLiteOpenHelper onCreate中得到NullPointerException？

Question

I have used LogCat to determine the problem line.

The SQL String I am trying to execute in onCreate is..

CREATE TABLE Routines(_id integer primary key autoincrement, json TEXT);

When it tries to execute this, the problem occurs.

This may well be whats causing the NullPointerException . If you can't see anything wrong with that, please read on for a bit more background.

This database has not been created yet, I keep getting a NullpointerException , I have compared this to previous SQLite code and the problem is proving evasive.

However, I mention this as it still has to go through the onCreate method. I create a new DatabaseOpenHelper (extending SQliteOpenHelper) in my main code and call the helper's open() method as seen below.

public void open() throws SQLException
{
    ssDatabase = databaseOpenHelper.getWritableDatabase();
}

If I am not mistaken, as my database has not been created (I made sure of that through uninstalling it prior). The onCreate SQLiteHelper is invoked when that open() method is called.

This is the code where I call that open method.

    try
    {                   
        dbConnector = new DatabaseConnector (this);
        debug = "2 ";

        // This on first start will invoke the database onCreate method - throws SQLException
        dbConnector.open();  /* PROBLEM LINE */
        debug = "3 ";
    }
    catch (Exception e)
    {
        textView1.setText(debug + e.toString());
    }

And this is the code containing my DatabaseOpenHelper and onCreate method

private class DatabaseOpenHelper extends SQLiteOpenHelper
{
    public DatabaseOpenHelper(Context context, String name, CursorFactory factory, int version)
    {
        super(context, name, factory, version); 

        Log.i(TAG, "Constructor");
    }

    // On initial creation of database
    @Override
    public void onCreate(SQLiteDatabase db)
    {
        Log.i(TAG, "Before SQL command");

        String sqlCreateCommand = "CREATE TABLE Routines"
                + "(_id integer primary key autoincrement, "
                + "json TEXT);";

        Log.i(TAG, sqlCreateCommand); 

        // I believe this to be the PROBLEM LINE
        ssDatabase.execSQL(sqlCreateCommand); 

        Log.i(TAG, "Jab done");
    }

    // On upgrade - currently do nothing
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
    {}      
}   

Thanks for the help!

Answer 1

seems like i dont have the prvilege to just post a comment. One question: ssDatabase.execSQL(sqlCreateCommand); --> shouldn't this be db.execSQL(sqlCreateCommand); since the parameter is SQLiteDatabase db. Secondly you use _id. is this index not created by default ? Nevermind if this has nothing to do with it. This were just my thoghts about it. :)