How do i get data from an SQLITE database to an array in android?

Question

Pretty sure this is an easy one, but i'm getting confused by all the examples that adapt the data returned from a cursor into different views. I just want to run a rawquery and put each item of data returned into a float array (so that i can add them up later). What do i need to use for this? Thanks

Solution 1

You'll still have a cursor when you query your database, but once you got the cursor you could iterate over it, pulling out the values you need into an array, like this:

DbAdapter db = new DbAdapter(mContext);
    int columnIndex = 3; // Whichever column your float is in.
    db.open();
    Cursor cursor = db.getAllMyFloats();
    float[] myFloats = new float[cursor.getCount()-1];

    if (cursor.moveToFirst())
    {                       
        for (int i = 0; i < cursor.getCount(); i++)
        {
            myFloats[i] = cursor.getFloat(columnIndex);
            cursor.moveToNext();
        }           
    }
    cursor.close();
    db.close();

    // Do what you want with myFloats[].

Solution 2

Don't minus by 1 in float[] myFloats = new float[cursor.getCount()-1]; because (int i =0) or i start from 0. If you use it, will appear Java.lang.IndexOutOfBoundsException. You need array index until [cursor.getCount()], not until [cursor.getCount()-1]. So the correct thing is float[] myFloats = new float[cursor.getCount()];

Comments

[Holly]

ahhh wicked thank you very much! The only thing i don't understand is the need to use columnIndex? I suppose i'll find out if i look into the method. I assume the actual rawQuery is done in getAllMyFloats right? Cheers this really helped.

[Holly]

oh also one other thing, do the columns start at an index of 0 or 1?

[John J Smith]

If you have a table with several columns, then you'll need the column index to get the specific data field you're looking for. Columns are zero-indexed.