Android SQLite Cursor out of bounds exception on SELECT count(*) FROM table

The following function is giving me an out of bounds exception...

public void count(){
    SQLiteDatabase db = table.getWritableDatabase();
    String count = "SELECT count(*) FROM table";
    Cursor mcursor = db.rawQuery(count, nul开发者_如何学Gol);
    int icount = mcursor.getInt(0);
    System.out.println("NUMBER IN DB: " + icount);
}

It's meant to return the number of rows in the database. Anybody know whats wrong? am I perhaps doing this task the wrong way?

You missed out

mcursor.moveToFirst();

public void count(){
    SQLiteDatabase db = table.getWritableDatabase();
    String count = "SELECT count(*) FROM table";
    Cursor mcursor = db.rawQuery(count, null);
    mcursor.moveToFirst();
    int icount = mcursor.getInt(0);
    System.out.println("NUMBER IN DB: " + icount);
}

But you should use better methods for this task, like the inbuilt helpers of DatabaseUtils

such as

public long count() {
    return DatabaseUtils.queryNumEntries(db,'tablename');
}

You might find helpful to use DatabaseUtils.longForQuery() to get the first column long value, when you have where query for the total count. It's simpler and you do not need that bunch of work with the Cursor.

need to move the cursor to the first (and only) row

Cursor mcursor = db.rawQuery(count, null);
mcursor.moveToFirst();
int icount = mcursor.getInt(0);

you can use this if you want to get Number of Rows for Specific ID or Value

public int numbersOfrows (int id) {
        SQLiteDatabase db = this.getReadableDatabase();
        int numbersOfrows = 0 ;

        Cursor c = db.rawQuery("select count(*) from table_name where Column_name = 'yourValue'")
        if (c.moveToFirst()){
            numbersOfrows = c.getInt(0);
        }

        return numbersOfrows ;
    }