How to retrieve single sqlite column and store rows into array

Question

Im new to android, and i use Sqlite to store an array of type double into a column called "KEY_VALUE"

public long createEntry(Double rates) { 
    ContentValues cv = new ContentValues();
    cv.put(KEY_VALUE, rates);
    return ourDatabase.insert(TABLE, null, cv);
}

I put the data into the columns here via another class

for(i=0;i<37;i++){
    entry.createEntry((theRSSHandler.rates()[i]));
    }

Now i would like to retrieve the column i saved and get each row as an array element, ive seen and tried other similar solutions but they have not worked. Here is the method i use to try and get the column data But it has failed.

public Double[] getData() {
    String[] col = {KEY_VALUE}; 
    Cursor c = ourDatabase.query(TABLE, col, KEY_VALUE , null, null, null, null);
    Double[] result = null;

    if(c != null){
        c.moveToFirst();
    }

    int iVal = c.getColumnIndex(KEY_VALUE);

    for(c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
        result[c.getPosition()] = c.getDouble(iVal);
    }
    return result;
}

it has failed...how? can you show the LogCat?

David M
– David M

2013-02-03 13:09:41 +00:00
Commented Feb 3, 2013 at 13:09 — David M
– David M, Commented Feb 3, 2013 at 13:09
it shows null pointer exception

user1559736
– user1559736

2013-02-03 13:11:53 +00:00
Commented Feb 3, 2013 at 13:11 — user1559736
– user1559736, Commented Feb 3, 2013 at 13:11

David M · Accepted Answer · 2013-02-03 13:12:49Z

1

you are trying to put values in an array that has not been initialized.

  Double[] result = null;

needs to be followed up with something like...

  result = new Double[100];

i think you probably want to initialize it with the number of records pointed to by the cursor

  result = new Double[c.count()];

answered Feb 3, 2013 at 13:12

David M

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1 Comment

David M Over a year ago

i could be slightly off on the syntax, as i'm doing this from memory (all my "good" code is at work.)

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